Bitcoin changes now come through soft forks, the method standardized in BIP 9. Soft forks maintain backward compatibility with older software. Nodes still running previous versions can continue operat
Bitcoin changes now come through soft forks, the method standardized in BIP 9. Soft forks maintain backward compatibility with older software. Nodes still running previous versions can continue operating on the network alongside upgraded nodes that follow the new rules. This backward compatibility means participation remains optional. Recent years have brought repeated proposals for hard forks, driven by efforts to increase the block size cap. A hard fork requires something more drastic: the entire network must transition from its current consensus rules to a new set of rules. In structural and technical terms, executing a hard fork resembles creating an alternative cryptocurrency. The new chain operates under different rules, and if people don't switch over, both versions exist in parallel. The conceptual line between these two phenomena is unclear.
What distinguishes a hard fork from an altcoin? Bitcoin.org defines a hard fork as "a permanent divergence in the block chain, commonly occurs when non-upgraded nodes can't validate blocks created by upgraded nodes that follow newer consensus rules." The terminology captures what happens in technical terms. Investopedia characterizes altcoins as "alternative cryptocurrencies launched after the success of Bitcoin." This definition is vaguer, offering less precision about what makes something an altcoin versus a standalone cryptocurrency.
The clearest difference involves coin distribution. When Bitcoin undergoes a hard fork, token holders keep their coins on both the original and new chains. Someone holding 10 bitcoin before a fork maintains 10 coins on each side after it occurs. New altcoins employ different distribution mechanisms. They launch through crowdsales, mining programs, or direct allocation rather than copying existing Bitcoin balances. Some figures in the cryptocurrency space, including Bitcoin Unlimited chief scientist Peter Rizun and the Augur team, have advocated launching new altcoins by mirroring Bitcoin's distribution at a specific block height. This strategy aims at piggybacking on Bitcoin's established network effect to boost adoption of a new token. The reasoning runs that if a coin starts with the same distribution as Bitcoin, it might inherit some of Bitcoin's momentum.
Yet coin distribution represents only the foundation of network value. How people evaluate and use a cryptocurrency determines its worth. If an entire network migrates to a hard-forked chain, that becomes Bitcoin. The old chain becomes an historical footnote. If migration splits between chains, the new one functions as an altcoin, regardless of technical intent. Some observers propose that SHA-256 hashing power provides the answer: whichever chain attracts the most mining power earns the right to the Bitcoin name. This argument collapses if a fork changes Bitcoin's proof-of-work algorithm. Two Bitcoin chains could coexist, one using SHA-256, one using an alternative hashing system. The alternative proof-of-work version might surpass the SHA-256 chain in value and activity. Which would then be Bitcoin?
These theoretical problems become practical ones during contentious forks. What happens when a hard fork divides support between the chains? Did the developers create an altcoin or execute a hard fork? The terminology fails to provide clarity. Which chain owns the right to the original name?
Ethereum worked through this dilemma. The DAO hack exposed a critical vulnerability in deployed smart contract code. The Ethereum team opted for a hard fork that reversed the stolen funds. Between 85 and 90 percent of participants switched to the new chain. The remaining 10 to 15 percent continued on the original blockchain, now branded Ethereum Classic. Which represents the authentic Ethereum? The cryptocurrency community answered through consensus. Most prominent developers, including Ethereum's creator, backed the hard-forked version. Media, exchanges, and users follow their lead. That chain is now Ethereum. Ethereum Classic became the name for the minority fork.
But what if the outcome had been reversed? If Ethereum Classic accumulated more market value and network activity than the primary Ethereum, would opinion flip? Would everyone call Ethereum Classic "Ethereum"? Here the Ethereum Foundation's trademark becomes material. The foundation holds "Ethereum" as a registered trademark in the United States and European Union. Legal action could prevent the term's reuse. Bitcoin faces no such constraint, lacking any trademark protection of its name.
This confusion may soon enter the real world. Grayscale Investments, the firm running the Bitcoin Investment Trust, plans to introduce an Ethereum Classic investment product. They're calling it the "Ethereum (ETC) Investment Trust." The naming illustrates how muddled the definitions have become in practice.
The fundamental difficulty is that you cannot determine in advance whether an action constitutes a hard fork, creates an altcoin, or does both. A fork that appears to have overwhelming community support can convert into an altcoin if support fractures later. Based on what happened with Ethereum, one pattern emerges: hard forks that fix protocol-level defects affecting the entire network avoid spawning altcoins. Other scenarios carry significant risk.
Aaron van Wirdum provided feedback for this article.
