SegWit (short for Segregated Witness) is a protocol upgrade that changes the way data is stored. It was activated on litecoin on May 10, 2017, and on bitcoin on 23 August, 2017. SegWit fixed the transaction malleability problem and also made some other improvements to the Bitcoin protocol possible. However, it still has a lot of critics and not all users of the Bitcoin network have welcomed the changes. Some members of the Bitcoin community disagree with SegWit so much that they’ve created their rival cryptocurrencies.