Segwit

Segwit, short for "Segregated Witness," is an upgrade to the Bitcoin protocol (and some other blockchains) that separates transaction signatures (witness data) from the transaction data. This change reduces the size of each transaction, allowing more transactions to fit into a block, which improves scalability. Segwit also fixes a vulnerability known as transaction malleability, enabling the development of second-layer solutions like the Lightning Network.