What is Bitcoin Core?

Bitcoin Core is the software that keeps Bitcoin operating smoothly. Originally known simply as “Bitcoin,” it was developed by Satoshi Nakamoto, and remains the reference client for Bitcoin. This means that it serves as the standard against which all other implementations of the Bitcoin protocol are measured.

“Bitcoin Core is the reference implementation of the bitcoin system, meaning that it is the authoritative reference on how each part of the technology should be implemented. Bitcoin Core implements all aspects of bitcoin, including wallets, a transaction and block validation engine, and a full network node in the peer-to-peer bitcoin network.” – Andreas Antonopoulos (2017)

Key Takeaways

• Bitcoin Core is the main software that defines and upholds the Bitcoin protocol, used by the vast majority (99%) of the network’s nodes.
• By running Bitcoin Core, users contribute to the network’s security and decentralization, reinforcing Bitcoin’s trustless nature.
• Bitcoin Core is open source, meaning anyone can contribute to its development, propose changes, and ensure transparency.
• Bitcoin Core has undergone significant development since its inception, with regular updates that enhance performance, security, and user accessibility.

By running Bitcoin Core, users actively participate in maintaining the Bitcoin network’s robustness. Moreover, Bitcoin Core’s open source nature allows developers from around the world to contribute to its improvement. This global collaboration enhances the decentralization of Bitcoin, preventing any single entity from gaining control over the network. As a reference implementation, Bitcoin Core also sets the standard for other Bitcoin-related projects, guiding the development of alternative software clients.

Click here to download Bitcoin Core.

Purpose of Bitcoin Core

The primary purpose of Bitcoin Core is to ensure the integrity and security of the Bitcoin network. It accomplishes this by performing several critical functions:

1. Operating a Node: Users can run a full node, allowing them to participate in the Bitcoin network by validating transactions and blocks according to Bitcoin’s consensus rules. This contributes to the decentralization and censorship resistance of Bitcoin.
2. Ensuring Security and Validation: The software enforces Bitcoin’s protocol rules, including transaction verification and block validation, and maintains the integrity of the blockchain.
3. Providing Wallet Functionality: The built-in wallet feature enables users to securely send, receive, and store bitcoin.
4. Managing the Network: It facilitates the management of peer-to-peer connections, ensuring efficient communication between nodes across the network.
5. Supporting Development: Serving as the foundation for Bitcoin protocol development, Bitcoin Core is the platform where changes to the protocol are proposed, reviewed, and implemented.
6. Generating Block Templates: Bitcoin Core provides block templates to mining nodes, which include valid transactions and necessary metadata. These templates are then used by miners to assemble and attempt to mine new blocks.
7. Assembling Blocks: Bitcoin Core aids in assembling valid transactions into blocks, setting the target difficulty and nonce before miners hash and submit them to the network.

Who Controls Bitcoin Core?

Bitcoin Core is not controlled by any single entity. Its development is guided by a global network of contributors and maintainers who collaborate to improve the software. The project’s open source nature ensures that no one can unilaterally make changes to the code without community consensus.

Maintainers play a crucial role in this process, but their power is limited. If they were to abuse their position, the community could easily fork the software and continue development independently. This structure ensures that Bitcoin Core remains true to the principles of decentralization and transparency.

How Bitcoin Core Has Evolved

Bitcoin Core has grown from a simple wallet and node software into a robust, multifaceted tool that powers the Bitcoin network. The original release contained just over 26,000 lines of code, but today, the codebase has expanded to over 750,000 lines. This growth reflects the ongoing efforts to enhance the software’s performance, security, and usability.

Key milestones in Bitcoin Core’s evolution include:

• Initial Release (v0.1): Satoshi Nakamoto released the first version of the Bitcoin software on January 9, 2009. This version laid the foundation for Bitcoin’s peer-to-peer network.
• Bug Fixes and Patches: Over the next year, Satoshi released several updates to address bugs and improve the software. These included fixes for issues related to the timechain’s reorganization and transaction handling.
• Handing Over: In late 2010, Satoshi handed over the reins to Gavin Andresen, who became the lead maintainer of Bitcoin Core. This marked the beginning of the transition from a single developer (Satoshi) to a more decentralized group of contributors.
• BIP Process Established: The Bitcoin Improvement Proposal (BIP) process was formalized to allow developers to propose, discuss, and implement changes to the Bitcoin protocol. BIP 001, created by Amir Taaki in 2011, provided a standardized process for Bitcoin development.
• P2SH Implementation: Gavin Andresen, Pieter Wuille, and others collaborated on the implementation of BIP 16, which introduced Pay-to-Script-Hash (P2SH). This feature allowed for more complex transaction types, such as multisignature transactions, and it improved Bitcoin’s flexibility.
• Rebranding: In 2014, to reduce confusion between Bitcoin, the network, and Bitcoin, the software, the software client was renamed “Bitcoin Core.” 
• Segregated Witness (SegWit): Introduced in 2017, SegWit (BIP141) was a major upgrade that improved Bitcoin’s scalability by separating transaction signatures from transaction data. This change allowed more transactions to fit into each block, enhancing the network’s efficiency.
• Taproot: Activated in 2021, Taproot (BIP 341) enhanced Bitcoin’s privacy and flexibility by allowing more complex transactions to be processed in a simplified manner. It also introduced Schnorr signatures, which improve the efficiency of multisignature transactions.

Development and Governance of Bitcoin Core

Bitcoin Core’s development is a decentralized and collaborative process. Since its inception, over a thousand developers have contributed to the project. The software is hosted on GitHub, where anyone can propose changes, report issues, or contribute code. This openness ensures that Bitcoin Core remains transparent and resistant to centralization.

New code is introduced through a formal process that often starts with discussions within the developer community. Significant changes are formalized into BIPs, which undergo extensive review and testing before they are accepted. Once approved, these changes are merged into the codebase by trusted maintainers. Major updates are released approximately every six months, ensuring that the software continues to evolve in response to the community’s needs.

What Do Bitcoin Core Developers Do?

Role of Maintainers: Maintainers are responsible for the upkeep of the Bitcoin Core codebase, which includes tasks like bug fixes, dependency updates, and maintaining compatibility and security. They spend most of their time on these maintenance tasks, prioritizing security for both their own projects and upstream dependencies.

Review and Decision Making: Maintainers critically review code and manage pull requests to ensure all changes are safe and do not disrupt network consensus. This involves careful evaluation before merging approved changes.

Evaluating Open Source Contributions: The project operates in an open source environment where anyone can submit code, reviews, or translations. There are no formal barriers to entry, allowing for a wide range of contributions from the global community.

Role Evolution and Release Process: The role of lead maintainer has evolved from a centralized position to being more distributed among several maintainers. This decentralization extends to the release process, which involves tagging commits, signing off on releases, and conducting merges via GitHub workflows.

Automated Checks and Balances: Development includes automated scripts that verify the authority of maintainers on changes, maintaining a secure and trusted contribution environment.

Community Decision-Making: Significant decisions, including the addition of new maintainers or the handling of controversial changes, involve extensive discussions within the Bitcoin Core community, primarily on platforms like IRC.

Bitcoin explained: Dev process: https://youtu.be/CJLxwmwL-fw?si=U4iFHkzXEENorjFM

How to Get Involved with Bitcoin Core

For those interested in contributing to Bitcoin Core, there are many ways to get involved. The Bitcoin Development Mailing List, GitHub repository, and various online forums are excellent starting points. Additionally, aspiring developers can take advantage of educational resources such as Mastering Bitcoin by Andreas Antonopoulos, and in-depth training programs offered by organizations like Base58 and Chaincode Labs.

Funding Bitcoin Core Development

In the early days of Bitcoin, development was largely voluntary. Today, many developers receive funding from organizations and foundations committed to supporting Bitcoin’s future. These entities, such as Blockstream, Chaincode Labs, and MIT’s Digital Currency Initiative, provide grants that allow developers to work on Bitcoin Core without commercial pressure. This funding model helps ensure that Bitcoin Core continues to evolve in a way that benefits the entire community.

Recap

Bitcoin Core is not just a piece of software; it’s the very foundation of the Bitcoin network. Through its decentralized development and open source nature, Bitcoin Core embodies the values of transparency, security, and financial sovereignty that are central to Bitcoin. As the network continues to grow and evolve, Bitcoin Core will remain a critical component of its success, driven by a global community of developers and users committed to the principles of decentralized finance. Whether you’re a seasoned developer or a curious newcomer, understanding Bitcoin Core is essential to understanding the future of money.