Segregated Witness (Segwit) was an idea that was introduced by the software developer, Peter Wuille, in 2015 at the Hong Kong Scaling Workshop. The protocol is meant to relocate witness inputs from the transaction hash, which will theoretically help malleability and create more block size space. The concept was at first well received by the bitcoin ‘community, ’ but some had hoped a block size increase would also follow. The community and developers couldn’t come to terms with increasing the block size, and lots of infighting began. Further, this meant the Segwit protocol sat on the shelf for quite some time as some miners would not approve of the upgrade unless a block size increase was included.
Full article here: https://news.bitcoin.com/segregated-witness-has-officially-activated-on-the-bitcoin-network