Bitcoin Gold is a hard fork of Bitcoin, the open source cryptocurrency. It is a open source, decentralized digital currency without a central bank or intermediary that can be sent from user to user on the peer-to-peer Bitcoin Gold network.

The stated purpose of the hard fork is to change the proof of work algorithm so that application specific integrated circuits (ASIC) can not be used to mine the Bitcoin Gold blockchain.

Bitcoin Gold hard forked from the Bitcoin blockchain on October 24, 2017, at block height 491407. 

Bitcoin Gold (BTG) Hard Fork Implements New Mining Algorithm in July 2018. The actual algorithm that was developed by Zcash was based on parameter set <200,9>. Bitcoin Gold has modified this algorithm and is now adopting parameter set <144,5>. This new algorithm is called Equihash-BTG. The new algorithm requires more memory than the one that was originally developed by Zcash.