What a fork is and why it is needed: the six basic forks of Bitcoin

Blockchain, which became the basis of Bitcoin, has existed since 2008 and for almost ten years of its existence has been repeatedly forked. The most famous new projects launched on the basis of Bitcoin can be considered six of them, each of which became an attempt by a part of the crypto-community to realize what they thought was missing from the original code.



During the existence of forco Bitcoin was much more , but most of them were not bringing something new - in fact, these projects were copies of Bitcoin, sometimes with minor differences.



The first known fork that created a truly separate project was Bitcoin XT.

Bitcoin xt

Fork occurred on August 19, 2015. The authors were the developers of the original Bitcoin Core - they created Bitcoin XT to solve the problem of network scaling. The developers of Bitcoin XT went by increasing the block size, which in the original Bitcoin chain was 1 MB.



At the time of the creation of the first Bitcoin XT block, it was supported by 12% of miners, however, according to the creators' idea, a complete transition required that 85% of the network nodes join the Bitcoin XT network. Later the share was reduced to 75%.



From the very beginning of its existence, the Bitcoin XT project faced harsh criticism of many leaders of the Bitcoin community. Moreover, the account allegedly owned by the creator of Bitcoin Satoshi Nakamoto spoke against the fork. However, back in 2014, the community spread information that the profile could have been hacked, and therefore there is no certainty that it was Satoshi who spoke out against Bitcoin XT.

Bitcoin unlimited

The Bitcoin Unlimited project appeared almost half a year later Bitcoin XT - in January 2016. He solved the same problem - increasing the block size - but in a fundamentally different way. Bitcoin Unlimited offered network nodes to independently decide what size blocks they should release. The creators have relied on democracy - everyone who has a complete node got the opportunity to express their opinion on the size of the block.



It was thought that the system itself would stop at the average value chosen by the majority: too small blocks would be “forked” from the network by the system itself, too large it would not accept at all, since most of the nodes would not see them.



The power of the free market, which rules the world of traditional economics and financial systems, was created by the creators of Bitcoin Unlimited to serve the digital economy. The influence of the project was added by the addition of the developers Tom Sonde and Tom Harding, who left Bitcoin XT, which had begun to break up, and Bitcoin Classic, which appeared a little later, but did not last long either.



Bitcoin Unlimited was not successful, like its predecessor Bitcoin XT, the community was worried about the prospect that the large centralized pools could take advantage of the proposed scheme, suppressing the opinion of the present majority of users with superior computing power. This would lead to a concentration of influence in the network in the hands of just a few groups and would devalue the whole idea of ​​Bitcoin as a decentralized system.



In addition, a large number of blocks of different sizes could lead to multiple involuntary forks and the formation of a number of false chains - which in the end would lead to the fall of Bitcoin itself.

Bitcoin classic

Bitcoin Classic appeared just a month later Bitcoin Unlimited, in February 2016, but began to crumble even faster. The creator of the fork was Gavin Andersen, the author of Bitcoin XT, who continues to pursue his goal - to increase the blockchain bandwidth by increasing the block size. This time it was planned to increase exactly twice, up to 2 MB, and two years later - up to 4 MB. Andersen was also joined by Jonathan Tumim, another co-creator of Bitcoin Core.



Unlike Bitcoin XT, Bitcoin Classic was accepted by the community favorably. The mining pools of Antpool (Bitmain), BW.COM, HAOBTC.com, Genesis Mining, Multipool.us, as well as Coinbase, OKCoin and Foldapp were in support of it. Roger Ver, the owner of Bitcoin.com, also expressed his sympathy for the project - he is confident that increasing the block size will create more complete nodes, which means that network decentralization will be further enhanced.



There were no direct and loud opponents for Bitcoin Classic, but it never became fully functional. The main reason for which discussions have been dragging on for the second year is the need to hold hard forks, which temporarily affect the overall security of the network and may end in a split. However, after the appearance of Bitcoin Cash, which produces blocks of up to 8 MB, the developers of Bitcoin Classic stated that they consider the goal to be achieved.

Bitcoin Cash

Bitcoin Cash is one of the loudest forks , really ending the split of the chain and the formation of a new cryptocurrency of the same name. It happened on August 1, 2017, and so far Bitcoin Cash shows good results in the market. Many experts are inclined to believe that while the authority of the original Bitcoin and associations with it keeps it afloat, even Bitcoin Cash itself has managed to gain some influence and steadfastly holds in the top ten most popular cryptocurrencies.



Bitcoin Cash has a number of significant differences from the original Bitcoin. There are three main code additions:

• block size limit increased from 1 MB to 8 MB at a time;
• installed additional protection against transaction failures - retries and erasures. Bitcoin Cash guarantees the safety of the user if two parallel chains are preserved - the code allows them to coexist, not duplicating and not erasing the operations;
• The type of transaction has changed. This is an integral part of the previous security code change - Bitcoin Cash has launched a new type of operation in which input values ​​are signed. This both ensures the security of hardware wallets, and solves the issue of quadratic hashing.

The creators of Bitcoin Cash are already planning two new hard forks in their own network - in the spring and autumn of 2018. Details have not been disclosed, but it is known that the forks will be aimed at an even greater increase in the size of the blocks.

Bitcoin gold

Bitcoin Gold is another cryptocurrency separated from Bitcoin on October 24, 2017, a day earlier than the date planned by the developers. The creators goal is to make their own cryptocurrency more powerful than the original Bitcoin, to turn it into real “digital gold”.



To achieve this goal, the authors changed the hashing algorithm by going to use proof of the work done by Equihash. The peculiarity of this PoW is that Equihash is suitable for GPU mining - mining cryptocurrency, passing through graphics cards. The same type of mining is already used in some other cryptocurrencies, in particular ZCash. In addition, Equihash is ASIC-resistant.



In fact, the creators of Bitcoin Gold are trying to expand the range of potential miners - the distribution and availability of GPU GPUs is higher than ASIC, and therefore there will be more users who can extract cryptocurrency and become network nodes. This will increase the level of decentralization and reduce the pressure on the community by large commercial mining pools. The main slogan - “Make Bitcoin decentalized again”, “Let's make Bitcoin decentralized again” is aimed at this. According to the developers, large pools have actually monopolized the network, and the community must fight this. The result of this struggle was Bitcoin Gold.



There were ideas and opponents insisting that the market for GPU-processors is controlled by only two major manufacturers, which means there is a risk again - but hardfork was still produced, and Bitcoin Gold is currently trading on the stock exchanges, albeit with a rather unstable course.

B2X

B2X, the brainchild of SegWit2x hard forks, was supposed to be another cryptocurrency. The fork was going to be held on November 16, 2017, it provoked heated discussions in the community, but was eventually canceled - the creators announced this in an open letter on November 8. However, officially it was not completely abolished, but was postponed for some time. A number of supporters also said that they continue to support SegWit2x even after canceling hard forks.



SegWit2X was supposed to create a new Bitcoin blockchain branch with a block size of 2 MB, a higher bandwidth and a low transaction cost. The resulting network was supposed to be a cryptocurrency analog of traditional Visa and Mastercard, and thus gain popularity among wide sections of users.



The main reason for the cancellation of hard forks the creators called the split of opinions - the next division broke the community, and the authors of SegWit2X are trying to avoid this by all means. In addition, some supporters of Segregated Witness, who later refused to support the agreement, stated that the conditions of the fork were non-transparent, there was no consensus between different groups and unfinished code.



The problem of increasing the size of a block in the main Bitcoin chain persists, and over time it becomes more acute. So, most likely, in the near future there will be new forks trying to win the sympathy of the community and change Bitcoin. In addition, the further, the more acute the problem of anonymity arises, which in the Bitcoin network is becoming increasingly illusory, and this issue also needs to be solved - which means there will be changes in this direction.