Bluesky (abbreviated as Bsky) is an American microblogging social media service. Users can share short posts containing text, images, and videos. It is owned by Bluesky Social PBC, a benefit corporation based in the United States.
Bluesky was developed as a reference implementation of the AT Protocol, an open communication protocol for distributed social networks. Bluesky Social promotes a composable user experience and algorithmic choice as core features of Bluesky. The platform offers a "marketplace of algorithms" where users can choose or create algorithmic feeds, user-managed moderation and labelling services, and user-made "starter packs" that allow users to quickly follow a large number of related accounts within a community or subculture. The AT Protocol offers a domain-name–based handle system within Bluesky, allowing users to self-verify an account's legitimacy and identity by proving ownership of a domain name.