Bech32 is a segwit address format specified by BIP 0173. This address format is also known as "bc1 addresses". Bech32 is more efficient with block space. As of October 2020, the Bech32 address format is supported in many popular wallets and is the preferred address scheme.
See the page Bech32 adoption to track adoption.
Examples of the address format being used on mainnet are the TXIDs
514a33f1d46179b89e1fea7bbb07b682ab14083a276979f91038369d1a8d689b. And addresses
- Talk by Pieter Wuille the new bech32 address format (March 2017) https://www.reddit.com/r/Bitcoin/comments/62fydd/pieter_wuille_lecture_on_new_bech32_address_format/
- Comment by maaku7 explaining how bech32 addresses improve the security of (for example) multisignature https://www.reddit.com/r/Bitcoin/comments/74tonn/bech32_native_segwit_address_already_used_on_the/dqlogru/