What Are Bitcoins Made Of? - bitcoins2025.com

What are Bitcoins Made Of? – An Introduction

Bitcoin is a digital or virtual currency designed to work as a medium of exchange. Unlike physical currencies like dollars or euros, which are issued and regulated by governments, Bitcoin operates on a decentralized peer-to-peer network, meaning no single institution controls it. This decentralization is a core feature distinguishing it from traditional fiat currencies.

Bitcoin’s existence relies entirely on cryptography and a distributed ledger technology known as blockchain. This makes it fundamentally different from physical money, which possesses tangible properties and relies on the trust placed in issuing authorities.

Bitcoin as a Cryptographic System

Bitcoin’s core functionality is built upon sophisticated cryptographic techniques. These techniques ensure the security and integrity of transactions. At its heart, Bitcoin uses cryptography to create digital signatures, verifying the ownership of Bitcoins and preventing double-spending. The blockchain, a continuously growing list of records, stores each transaction securely and transparently. Each block in the chain contains cryptographic hashes of the previous block, linking them together in a chronological and tamper-evident manner. This cryptographic chain provides a high level of security, making it extremely difficult to alter or forge past transactions. The cryptographic algorithms used are publicly known and rigorously tested, adding to the system’s overall transparency and security. Mining new Bitcoins involves solving complex cryptographic puzzles, which requires significant computational power and contributes to the network’s security. These cryptographic processes are essential to Bitcoin’s operation and underpin its value proposition as a secure and transparent digital currency.

The Technology Behind Bitcoin: What Are Bitcoins Made Of

Bitcoin’s revolutionary nature stems not from its inherent value, but from the innovative technology underpinning it: the blockchain. This decentralized, public ledger records every Bitcoin transaction, ensuring transparency and security in a way traditional financial systems struggle to match. Understanding the blockchain is key to understanding Bitcoin itself.

The blockchain is essentially a continuously growing list of records, called blocks, linked together chronologically and secured cryptographically. Imagine a chain of interconnected blocks, each block containing a batch of recent Bitcoin transactions. This chain is distributed across a vast network of computers, making it incredibly resilient to tampering or single points of failure.

Block Structure and Chain Formation

Each block in the blockchain contains a timestamp, a hash (a unique digital fingerprint) of the previous block, and a set of validated Bitcoin transactions. This linking of blocks through their hashes creates the “chain,” ensuring the integrity of the entire record. If someone tries to alter a transaction in a past block, the subsequent hashes would also change, immediately revealing the tampering. This inherent structure provides a robust system for maintaining the accuracy and immutability of the Bitcoin transaction history. The process of adding a new block to the chain is known as “mining,” a computationally intensive process that secures the network and ensures the integrity of the system.

Transaction Verification and Addition to the Blockchain

Before a Bitcoin transaction is added to a block, it must undergo a rigorous verification process. This involves the network of computers (nodes) checking the validity of the transaction, ensuring the sender has sufficient funds and that the transaction details are accurate. Once a sufficient number of nodes confirm the transaction’s validity, it is included in a block awaiting addition to the chain. This consensus mechanism, often using a proof-of-work system in Bitcoin’s case, prevents fraudulent transactions from being added to the blockchain. The computational power required to create a new block and add it to the chain acts as a deterrent against malicious actors.

Analogy: A Publicly Accessible, Tamper-Proof Ledger

Imagine a shared, publicly accessible notebook where every financial transaction is recorded. Each page in the notebook represents a block, and the pages are linked together sequentially. Every time a new transaction occurs, it’s written on the next available page, and the notebook is distributed to everyone in the group. Because everyone has a copy, no single person can alter past entries without everyone else noticing the discrepancy. This shared, publicly accessible, and tamper-proof nature of the notebook mirrors the functionality of the Bitcoin blockchain. The cryptographic security adds an extra layer of protection, making it practically impossible to alter the recorded information without detection.

Mining Bitcoins

Bitcoin mining is the process by which new bitcoins are created and added to the blockchain, the public ledger that records all bitcoin transactions. It’s a computationally intensive process that requires specialized hardware and significant energy consumption. Essentially, miners compete to solve complex mathematical problems, and the first to solve the problem gets to add the next block of transactions to the blockchain and is rewarded with newly minted bitcoins.

The process involves powerful computers running sophisticated algorithms designed to solve cryptographic hash functions. These algorithms are designed to be extremely difficult to solve, requiring vast computational power to find the solution within a reasonable timeframe. The difficulty of these problems is adjusted periodically by the Bitcoin network to maintain a consistent rate of new bitcoin creation, roughly every ten minutes.

Computational Power and Mining

The ability to mine bitcoins successfully is directly proportional to the computational power a miner possesses. Computational power, often measured in hashes per second (H/s), represents the speed at which a computer can perform these complex calculations. Miners with more powerful hardware can perform more calculations per second, increasing their chances of solving the cryptographic puzzle and earning the bitcoin reward. This creates a competitive landscape where miners constantly seek more powerful hardware to maintain profitability. For example, a miner with a hash rate of 100 TH/s (terahashes per second) has a significantly higher chance of successfully mining a block compared to a miner with only 1 GH/s (gigahashes per second).

Energy Consumption in Bitcoin Mining

Bitcoin mining is an energy-intensive process. The computational power required to solve the cryptographic problems translates to a high level of electricity consumption. The environmental impact of this energy consumption has been a subject of ongoing debate and scrutiny. The amount of energy used varies significantly depending on the hardware used, the efficiency of the mining operation, and the price of electricity. Estimates of Bitcoin’s total energy consumption vary widely, highlighting the complexities and uncertainties involved in accurately measuring this figure. For instance, some estimates suggest a significant portion of mining operations leverage renewable energy sources, offsetting some of the environmental impact.

Bitcoin Mining Hardware

A range of hardware is used for Bitcoin mining, each with varying levels of computational power and energy efficiency. Initially, standard CPUs were sufficient, but as the difficulty increased, specialized hardware became necessary.

Application-Specific Integrated Circuits (ASICs) are currently the dominant hardware used for Bitcoin mining. ASICs are custom-designed chips optimized for performing the specific cryptographic hash functions used in Bitcoin mining. They are significantly more efficient and powerful than CPUs or GPUs for this task. ASICs are manufactured by specialized companies and are generally not accessible to individual hobbyist miners due to their high cost and technical complexity. For example, Bitmain’s Antminer series is a well-known example of high-performance ASIC miners.

Graphics Processing Units (GPUs), initially popular for Bitcoin mining, have largely been superseded by ASICs due to their lower efficiency. While GPUs can still be used for mining some alternative cryptocurrencies (altcoins), their profitability in Bitcoin mining is significantly lower compared to ASICs.

Field-Programmable Gate Arrays (FPGAs) offer a degree of flexibility, allowing for reprogramming to adapt to different algorithms. However, their performance generally falls between ASICs and GPUs for Bitcoin mining, making them less competitive in terms of profitability.

Bitcoin’s Security and Decentralization

Bitcoin’s security and decentralized nature are intrinsically linked, forming the bedrock of its operation and value proposition. These features differentiate it significantly from traditional financial systems, offering both advantages and unique vulnerabilities. Understanding these aspects is crucial to grasping Bitcoin’s potential and limitations.

Cryptography underpins Bitcoin’s security, ensuring the integrity and confidentiality of transactions. The system relies on sophisticated cryptographic algorithms to protect against unauthorized access and manipulation. This robust cryptographic framework is vital for maintaining trust and confidence in the network.

Cryptography’s Role in Securing Bitcoin Transactions

Bitcoin transactions are secured through several cryptographic techniques. Public-key cryptography allows users to generate a pair of keys: a public key, shared publicly, and a private key, kept secret. The public key acts like a digital address, while the private key is necessary to authorize transactions. Each transaction is digitally signed using the sender’s private key, proving authenticity and preventing unauthorized spending. The blockchain itself, a distributed ledger, further enhances security by recording every transaction permanently and transparently, making it extremely difficult to alter past records. The cryptographic hash function, a one-way function that transforms data into a unique fingerprint, ensures the integrity of each block in the chain. Any attempt to alter a transaction would change its hash, immediately making the alteration detectable by the network.

Decentralization and Bitcoin’s Stability

Bitcoin’s decentralized architecture is a key differentiator from traditional financial systems. Instead of relying on a central authority like a bank, Bitcoin operates on a peer-to-peer network. This means there is no single point of failure or control. Transactions are verified by numerous nodes across the globe, making the system highly resilient to censorship and single points of failure. This decentralization contributes to Bitcoin’s stability by reducing the risk of manipulation or control by any single entity. However, the decentralized nature also presents challenges, as it relies on the collective participation of nodes to maintain the network’s integrity and security.

Potential Vulnerabilities and Mitigation Strategies

While Bitcoin’s design incorporates strong security measures, potential vulnerabilities exist. These include the risk of 51% attacks, where a single entity controls more than half of the network’s computing power, allowing them to potentially manipulate the blockchain. However, the massive computing power required to achieve this makes such attacks extremely costly and difficult. Furthermore, vulnerabilities in individual wallets or exchanges, due to software bugs or user error, can lead to loss of funds. Mitigation strategies include using reputable wallets and exchanges, employing strong security practices, and regularly updating software. Another potential vulnerability lies in the potential for quantum computing to break current cryptographic algorithms in the future. Research and development of quantum-resistant cryptography are underway to address this long-term threat.

Comparison of Bitcoin’s Security to Traditional Financial Systems, What Are Bitcoins Made Of

Compared to traditional financial systems, Bitcoin offers a different security model. Traditional systems rely on centralized institutions and regulatory frameworks, while Bitcoin relies on cryptography and decentralization. While traditional systems are vulnerable to fraud, hacking, and regulatory manipulation, Bitcoin’s decentralized nature makes it more resistant to these threats. However, Bitcoin lacks the regulatory oversight and consumer protection mechanisms found in traditional financial systems, meaning users bear more responsibility for securing their own funds. The security of each system relies on different assumptions and presents different types of risks.

The Components of a Bitcoin Transaction

A Bitcoin transaction, at its core, is a digital record of value transfer between two or more Bitcoin addresses. Understanding its components is crucial to grasping how Bitcoin operates securely and transparently on the blockchain. Each element plays a vital role in verifying the transaction’s legitimacy and preventing fraudulent activity.

Each transaction includes several key components that work together to ensure its validity and security within the Bitcoin network. These components are digitally signed and cryptographically secured, making them tamper-proof and auditable.

Transaction Inputs

Transaction inputs represent the funds being spent. Each input references a previous transaction’s output, specifically identifying the unspent transaction output (UTXO) that is being used to fund the current transaction. This UTXO model ensures that each Bitcoin can only be spent once. Think of it like cash – you can’t spend the same dollar bill twice. The input also includes a digital signature proving the owner’s authorization to spend the UTXO. This signature is created using the private key associated with the Bitcoin address controlling the UTXO.

Transaction Outputs

Transaction outputs specify where the funds are being sent. Each output defines a Bitcoin address and the amount of Bitcoin being sent to that address. A single transaction can have multiple outputs, allowing the sender to distribute funds to different recipients simultaneously. Outputs remain unspent until they are used as inputs in a future transaction. They form the basis of the UTXO model.

Transaction Fees

Bitcoin transactions require a small fee to incentivize miners to include them in a block. This fee is paid by the sender and is typically a small fraction of a Bitcoin. The fee amount is determined by network congestion; higher congestion means higher fees to prioritize inclusion in a block. Miners prioritize transactions with higher fees, ensuring timely processing even during periods of high network activity.

Digital Signatures

Digital signatures are crucial for verifying the authenticity and integrity of a transaction. Each input includes a digital signature created using the sender’s private key. This signature cryptographically proves that the sender possesses the private key associated with the Bitcoin address controlling the funds being spent. It ensures that only the legitimate owner can authorize the transaction.

Example Bitcoin Transaction

Let’s say Alice wants to send 0.5 BTC to Bob. Alice’s previous transaction resulted in a UTXO of 1 BTC at her address.

The transaction would then be broadcast to the Bitcoin network, where miners verify the signatures and add it to a block in the blockchain. After confirmation, the transaction is considered final and irreversible.

Bitcoin’s Value and Volatility

Bitcoin’s value, unlike traditional currencies backed by governments, is determined solely by supply and demand within its decentralized market. This dynamic leads to significant price fluctuations, often described as volatility. Understanding the factors driving these changes is crucial for anyone engaging with the cryptocurrency.

The price of Bitcoin is influenced by a complex interplay of factors. News events, regulatory changes, technological advancements, market sentiment, and even macroeconomic conditions all contribute to its fluctuating value. For example, positive news about Bitcoin adoption by major corporations or favorable regulatory decisions in key markets can trigger price increases, while negative news, such as security breaches or government crackdowns, can lead to sharp declines. Furthermore, the overall economic climate and investor confidence in the global financial system can also impact Bitcoin’s appeal as an alternative asset. The limited supply of Bitcoin, capped at 21 million coins, also plays a significant role, potentially driving up prices as demand increases.

Market Capitalization and Bitcoin’s Worth

Market capitalization, calculated by multiplying the current price of Bitcoin by the total number of Bitcoins in circulation, provides a measure of Bitcoin’s overall market value. This figure reflects the total worth of all Bitcoins currently held by investors. A rising market capitalization generally indicates increasing investor confidence and a higher perceived value of Bitcoin. Conversely, a falling market capitalization suggests waning interest and a potential decrease in value. It’s important to note that market capitalization doesn’t directly translate to Bitcoin’s inherent worth, but rather reflects the collective assessment of its value by market participants.

Bitcoin’s Volatility Compared to Other Assets

Bitcoin is notoriously volatile compared to traditional assets like gold or stocks. While gold prices tend to fluctuate relatively slowly, influenced by factors like inflation and industrial demand, Bitcoin’s price can experience significant swings in a short period. Similarly, while stocks can be volatile, their price movements are often influenced by factors like company performance, industry trends, and macroeconomic conditions, which are often more predictable than the forces driving Bitcoin’s price. The difference lies in the relative maturity and regulation of these markets. The Bitcoin market is still relatively young and less regulated, making it more susceptible to speculative trading and dramatic price swings.

Hypothetical Scenario: News Impact on Bitcoin Price

Imagine a scenario where a major global bank announces plans to integrate Bitcoin into its payment system. This positive news would likely trigger a surge in demand for Bitcoin, as investors rush to acquire the cryptocurrency. The increased demand would drive up the price, potentially leading to a significant percentage increase within a short timeframe. Conversely, if the same bank announced it was halting all Bitcoin-related activities due to regulatory concerns, the opposite effect would occur. Fear and uncertainty would likely lead to a sell-off, resulting in a sharp decline in Bitcoin’s price. This hypothetical scenario illustrates how even a single piece of news can significantly impact Bitcoin’s volatility.

Visual Representation of a Bitcoin Transaction

Understanding how a Bitcoin transaction flows through the network is crucial to grasping its decentralized nature. The following description and accompanying conceptual illustration depict a simplified, yet representative, Bitcoin transaction. Note that this is a simplified model; real-world transactions involve more complex interactions.

A Bitcoin transaction begins with a sender initiating a payment to a recipient. This involves broadcasting the transaction details to the network. The transaction then propagates across the network, reaching numerous nodes. These nodes verify the transaction’s legitimacy. Finally, miners compete to include the verified transaction in a block, which is then added to the blockchain.

Transaction Flow

Imagine a diagram showing a series of connected boxes. The first box, labeled “Sender,” contains information about the sender’s Bitcoin address and the amount being sent. An arrow points from this box to the next, labeled “Network Broadcast.” This box represents the transaction data being sent across the peer-to-peer Bitcoin network. Multiple arrows emanate from this box, pointing to numerous smaller boxes representing “Nodes.” Each Node box depicts a computer on the Bitcoin network verifying the transaction’s validity. This verification involves checking the sender’s balance, ensuring the digital signature is correct, and confirming that the transaction hasn’t already been spent (double-spending prevention).

From the Nodes, another arrow leads to a larger box labeled “Miners.” This box depicts multiple computers competing to solve complex cryptographic puzzles to add the transaction to a new block in the blockchain. The first miner to solve the puzzle adds the transaction to their block and broadcasts it to the network. The successful miner receives a reward in Bitcoin. Another arrow then points from the “Miners” box to a final box representing the “Blockchain.” This box represents the ever-growing, publicly accessible, and chronologically ordered ledger of all Bitcoin transactions. The added block containing the transaction becomes part of the immutable blockchain. The final arrow points from the “Blockchain” box to the “Recipient,” indicating the successful completion of the transaction.

Verification and Confirmation

The verification process is critical. Nodes on the network independently verify the transaction using the blockchain’s history. They check if the sender has sufficient funds and if the digital signature is valid. This process ensures the transaction’s authenticity and prevents fraudulent activity. Once a sufficient number of nodes have verified the transaction and it’s included in a block added to the blockchain, the transaction is considered confirmed. The confirmation process typically requires multiple block confirmations to enhance security and reduce the risk of reversal. The more confirmations, the lower the likelihood of the transaction being reversed through a potential chain reorganization (though highly improbable given the network’s size and security).

Caption for the Visual Representation

This diagram illustrates a simplified Bitcoin transaction flow. A sender initiates a transaction, broadcasting it to the network’s nodes for verification. Miners compete to add the verified transaction to a block in the blockchain, which is then added to the ever-growing, publicly accessible, and immutable record of all Bitcoin transactions. The process involves several stages of verification, ensuring the transaction’s integrity and security. The successful addition of the transaction to the blockchain signifies the completion of the payment to the recipient. The decentralized and transparent nature of the Bitcoin network is fundamental to its security and operation.

Frequently Asked Questions (FAQ)

This section addresses some common queries regarding Bitcoin, covering its practical use, legal standing, and security aspects. Understanding these points is crucial for anyone considering engaging with this digital currency.

Bitcoin Wallets

A Bitcoin wallet is a software program or device that allows users to manage and transact with their Bitcoins. It doesn’t actually store Bitcoins themselves – instead, it securely stores the private keys needed to access and control the Bitcoins held in associated addresses on the Bitcoin blockchain. There are several types of Bitcoin wallets, each offering varying levels of security and convenience. Hardware wallets, for example, offer the highest level of security by storing private keys offline, while software wallets, accessible via computers or smartphones, are more convenient but potentially less secure if not properly protected. Paper wallets, a printed record of the public and private keys, represent a different approach to security and accessibility. The choice of wallet depends on individual needs and risk tolerance.

Acquiring Bitcoins

Several methods exist for purchasing Bitcoins. The most common involve using Bitcoin exchanges, which are online platforms that facilitate the buying and selling of Bitcoin using fiat currencies (like USD, EUR, etc.). These exchanges typically require users to create an account and verify their identity. Another method is peer-to-peer (P2P) trading, where individuals can buy and sell Bitcoin directly to each other, often using escrow services to ensure secure transactions. Some businesses also accept Bitcoin as payment for goods and services. Finally, it’s possible to “mine” Bitcoins, though this requires significant computational resources and energy, and is not a practical method for most individuals.

Bitcoin’s Legal Status

The legal status of Bitcoin varies significantly across jurisdictions. Some countries have fully embraced Bitcoin, regulating it as a commodity or virtual currency, while others maintain a more cautious approach, with varying degrees of regulation or even outright bans. In many jurisdictions, the focus is on combating illicit activities like money laundering and terrorist financing, rather than outright prohibiting the use of Bitcoin itself. It’s essential to research the specific legal framework in your country or region before engaging with Bitcoin. For example, Bitcoin is legal in the United States, but regulations vary across states. In some countries in Asia, the legal status remains ambiguous or under constant review.

Bitcoin Security

Bitcoin’s security rests on its cryptographic foundation and decentralized nature. The blockchain’s immutability and the consensus mechanism (proof-of-work) make it incredibly difficult to alter transaction records or double-spend Bitcoins. However, risks still exist. Loss of private keys renders Bitcoins irretrievably lost. Exchanges and online wallets can be vulnerable to hacking, and users should choose reputable providers and employ strong security practices. Phishing scams and malware pose further threats. Therefore, while Bitcoin’s underlying technology is secure, user responsibility plays a vital role in mitigating risks. Implementing robust security measures such as two-factor authentication and using secure wallets is crucial for protecting Bitcoin holdings.

Beyond the Basics

Having covered the fundamentals of Bitcoin, let’s delve into some more advanced concepts that provide a deeper understanding of its complexities and future potential. This section explores key developments and emerging trends shaping the Bitcoin landscape.

Bitcoin Forks and Their Implications
Bitcoin forks occur when the Bitcoin blockchain splits into two separate chains, each with its own set of rules and history. This typically happens due to disagreements within the Bitcoin community regarding protocol upgrades or changes. A hard fork creates a completely new cryptocurrency, while a soft fork maintains backward compatibility with the original blockchain. A notable example is Bitcoin Cash (BCH), which emerged from a hard fork of Bitcoin. The implications of forks can be significant, potentially leading to increased competition, new innovations, or even fragmentation within the Bitcoin ecosystem. Forks can introduce new features or address scalability issues, but they also carry the risk of creating confusion and potentially diluting the value of the original cryptocurrency.

Bitcoin Forks: Hard Forks and Soft Forks

Hard forks result in two distinct cryptocurrencies, each with its own blockchain and rules. The original blockchain continues, and a new, separate blockchain is created. Soft forks, on the other hand, are backward compatible. Nodes running the old software can still validate transactions on the updated blockchain. The success of a fork depends on community adoption and the perceived value of the new cryptocurrency.

The Lightning Network: Enhancing Transaction Speed

The Lightning Network is a second-layer scaling solution designed to address Bitcoin’s scalability limitations. It operates on top of the main Bitcoin blockchain, enabling faster and cheaper transactions by creating off-chain payment channels. These channels allow users to exchange Bitcoins without broadcasting each transaction to the entire network. This significantly reduces transaction fees and increases transaction speed, potentially facilitating micropayments and wider adoption. Imagine a scenario where you could pay for a cup of coffee instantly using Bitcoin without incurring substantial transaction fees; this is the potential of the Lightning Network.

Emerging Trends and Developments

The Bitcoin ecosystem is constantly evolving. Several significant trends are shaping its future. One key development is the increasing institutional adoption of Bitcoin as a store of value and a hedge against inflation. Major corporations and financial institutions are beginning to incorporate Bitcoin into their investment strategies. Another trend is the growth of decentralized finance (DeFi) applications built on top of Bitcoin, expanding its functionality beyond simple peer-to-peer transactions. Moreover, research into improving Bitcoin’s scalability and energy efficiency continues, potentially leading to further technological advancements.

Bitcoin’s Future and Global Economic Impact

Predicting Bitcoin’s future is inherently speculative, but several factors suggest a potentially significant impact on the global economy. Its decentralized nature and limited supply could position it as a robust alternative to traditional financial systems. Widespread adoption could disrupt existing financial institutions and reshape international trade. However, challenges remain, including regulatory uncertainty and the need for greater user-friendliness. The ongoing development and adoption of technologies like the Lightning Network are crucial in determining Bitcoin’s long-term success and its potential to transform global finance. The impact on global economies will depend heavily on regulatory frameworks and the level of public and institutional adoption.

What Are Bitcoins Made Of – Bitcoin, fundamentally, is a complex string of code, a digital asset existing only as data on a distributed ledger. Understanding its composition helps us grasp the implications of its scarcity; to know precisely how many Bitcoin exist, one should consult resources like this helpful guide: How Many Bitcoin Exist. This limited supply, coupled with its unique digital nature, is a core component of Bitcoin’s value proposition.

Bitcoins, fundamentally, are lines of code representing digital currency. Understanding their composition leads to the question of their creation; to find out the daily rate of new Bitcoin entering circulation, check this resource on How Many Bitcoins Mined Per Day. This daily addition, however, doesn’t change the underlying code that defines what a Bitcoin actually is.

Bitcoins aren’t made of physical materials; they’re lines of code, entries on a public ledger. Understanding how they’re created involves grasping the concept of “mining,” which is essentially solving complex mathematical problems. To learn more about this process, check out this resource on What Is A Bitcoin Mine. Ultimately, the “substance” of a Bitcoin is the cryptographic proof of its existence and ownership, verified across a decentralized network.

Bitcoin, unlike physical currency, isn’t made of paper or metal; it’s a digital asset based on cryptography. Understanding its underlying technology is key to grasping its value, and to see its current market price, check out the latest figures on Cost Of Bitcoin Today. This fluctuating price directly reflects the demand and perceived value of this complex, decentralized system built on cryptographic principles and a finite supply.

Therefore, what Bitcoin is “made of” fundamentally influences its cost.

Bitcoin, fundamentally, is a complex algorithm and cryptographic keys, not a physical thing. Understanding its creation involves grasping the mining process, which is directly impacted by the halving events; to learn more about the timing of the next halving, check out this resource on When Is Bitcoin Halving 2025. The halving affects the rate at which new Bitcoins are created, thus influencing the overall supply and ultimately contributing to the unique characteristics of what makes up a Bitcoin.