When did the main Bitcoin client become known as Bitcoin Core? When/Why/How did this happen? Afaik at some point in 2014/2015, Bitcoin became known as 'Bitcoin Core'. I assume this was to differentiate it from other implementations of Bitcoin.
When and how did this decision come about?
The renaming was merged in December 2013 with prior discussion on this GitHub issue. The general motivation was to distinguish between one particular implementation of the Bitcoin protocol (many refer to Bitcoin Core as the &quot;reference implementation&quot;) versus other implementations (libbitcoin, btcd, bcoin, bitcoin-s etc) that either existed at the time or came later.
At the time most of the well known altcoins (Litecoin, Dogecoin etc) didn't hard fork the Bitcoin blockchain. They started their blockchain from a different genesis block to Bitcoin. The well known hard forks came later in 2017 with BCH, BSV etc.