SegWit

Segregated Witness, or SegWit, is the name used for an implemented soft fork change in the transaction format of Bitcoin.

[1] The declared purpose was to prevent nonintentional bitcoin transaction malleability, allow optional data transmission, and to bypass certain protocol restrictions (such as the block size limit) with a soft fork.

It does this by splitting the transaction into two segments, removing the unlocking signature ("witness" data) from the original portion and appending it as a separate structure at the end.

[3] The original section would continue to hold the sender and receiver data, and the new "witness" structure would contain scripts and signatures.

A new block is added to the chain at random intervals averaging, by design, ten minutes (proof of work causes this delay).

[8] The signature data called the witness would be separated from the Merkle tree record of who is sending or receiving the bitcoins.

[citation needed] In the first week of October, the proportion of network transactions using SegWit rose from 7% to 10%, indicating an increase in use rate.

In May 2017, Digital Currency Group (not to be confused with the Digital Currency Initiative of the MIT Media Lab) announced it had offered a proposal, referred to as SegWit2x ("the New York Agreement"), activating Segregated Witness at an 80% threshold of the total bitcoin hash rate, signaling at bit 4; and activating a 2 MB block size limit within six months with support in excess of 80% of the total bitcoin hash rate.

In mid-July 2017, it became evident that miners favored implementing the Segwit part of the agreement before the 1st of August 2017 UASF, aiming to mitigate the risk of a hard fork in the bitcoin network.