SegWit (Segregated Witness, SegWit) translates as "segregated witness" and is an update to the bitcoin protocol developed by members of the core development team. Technically it is a soft fork, a soft update in which the new rules are compatible with the old ones: the chain of blocks is not broken, and nodes that have not switched to the new version continue to consider the blocks valid.

Why SegWit is needed

The essence of the innovation is that signature data (the witnesses confirming the right to dispose of coins) is moved into a separate structure and no longer takes up space in the main part of the block. Thanks to this, more transactions fit into a single block without a formal increase in its size. This is aimed at reducing the load on the network and using block space more efficiently.

• Increasing throughput without a hard increase in block size.
• Reducing the impact of the problem of blocks being overloaded with transactions.
• Eliminating the vulnerability associated with the malleability of transaction identifiers, which is important for second-layer solutions.

SegWit became an important step in the development of the network and was subsequently implemented in a number of other cryptocurrencies that use a similar architecture.