What is a SegWit address?

A SegWit address is a Bitcoin address that uses Segregated Witness, a 2017 protocol upgrade that moves signature data out of the main transaction body. SegWit addresses start with bc1 (native, called bech32) or with 3 (wrapped). By separating the witness data, SegWit lowers transaction fees and lets more transactions fit in a block. For example, sending Bitcoin from a bc1 address typically costs less than from an older address beginning with 1. The format is a technical standard, not specific to any platform.