History of bitcoin

On 18 August 2008, the domain name "bitcoin.org" was registered.[25] In November that year, a link to a paper authored by Satoshi Nakamoto titled Bitcoin: A Peer-to-Peer Electronic Cash System[4] was posted to a cryptography mailing list. Nakamoto implemented the bitcoin software as open source code and released it in January 2009 on SourceForge.[26][27][12] The identity of Nakamoto remains unknown.[11]

In January 2009, the bitcoin network came into existence after Satoshi Nakamoto mined the first ever block on the chain, known as the genesis block.[28][29] Embedded in the coinbase of this block was the following text:

The Times 03/Jan/2009 Chancellor on brink of second bailout for banks.[12]

This note has been interpreted as both a timestamp of the genesis date and a derisive comment on the instability caused by fractional-reserve banking.[30]:18

The receiver of the first bitcoin transaction was cypherpunk Hal Finney, who created the first reusable proof-of-work system (RPOW) in 2004.[31] Finney downloaded the bitcoin software the day it was released, and received 10 bitcoins from Nakamoto.[32][33] Other early cypherpunk supporters were Wei Dai, creator of bitcoin predecessor b-money, and Nick Szabo, creator of bitcoin predecessor bit gold.[34]

In the early days, Nakamoto is estimated to have mined 1 million bitcoins.[35] In 2010, Nakamoto handed the network alert key and control of the Bitcoin Core code repository over to Gavin Andresen, who later became lead developer at the Bitcoin Foundation.[36] Nakamoto subsequently disappeared from any involvement in bitcoin.[37] Andresen stated he then sought to decentralize control, saying: "As soon as Satoshi stepped back and threw the project onto my shoulders, one of the first things I did was try to decentralize that. So, if I get hit by a bus, it would be clear that the project would go on."[37] This left opportunity for controversy to develop over the future development path of bitcoin.[38]

Altcoins
There have been several spin offs of bitcoin, known as altcoins of alternative coins, that have separate blockchains. One early altcoin was Litecoin, which began in October, 2011. Since then there have been numerous altcoins created as interest in cryptocurrency has increased.

Forks
See also: Fork (blockchain) and List of bitcoin forks
On 1 August 2017, a hard fork of bitcoin was created, known as Bitcoin Cash.[39] Bitcoin Cash has a larger block size limit and had an identical blockchain at the time of fork. On 24 October 2017 another hard fork, Bitcoin Gold, was created. Bitcoin Gold changes the proof-of-work algorithm used in mining.[40]

Scaling Debates
As disagreements around scaling bitcoin heated up, several hard forks were proposed. Bitcoin XT was one proposal that aimed for 24 transactions per second. In order to accomplish this, it proposed increasing the block size from 1 megabyte to 8 megabytes. When Bitcoin XT declined, some community members still wanted block sizes to increase. In response, a group of developers launched Bitcoin Classic, which intended to increase the block size to only 2 megabytes. Bitcoin Unlimited set itself apart by allowing miners to decide on the size of their blocks, with nodes and miners limiting the size of blocks they accept, up to 16 megabytes.

Segwit Soft-fork
Bitcoin Core developer Peter Wuille presented the idea of Segregated Witness (SegWit) in late 2015. Put simply, SegWit is a backward-compatible soft-fork that aims to reduce the size of each bitcoin transaction, thereby allowing more transactions to take place at once. Segwit activated on 1 August 2017.

In response to SegWit, some developers and users decided to initiate a hard fork in order to avoid the protocol updates it brought about. Bitcoin Cash was the result, which increased the block size to 8 megabytes.[41] However, there was another proposed hard fork called Segwit2x, which would have increased the block size to 2 megabytes. After a number of companies and individuals in the community decided to back out of the hard fork, the team behind SegWit2x cancelled their planned hard fork in November 2017.

New Features
Bitcoin Gold was a hard fork that followed several months later in October 2017 that changed the proof-of-work algorithm with the aim of restoring mining functionality to basic graphics processing units (GPU), as the developers felt that mining had become too specialized.[42] Bitcoin Private, launched in March 2018, added the ability to keep certain details private in a transaction, in contrast to bitcoin which has a transparent transaction history.