Flock is a web browser built on Mozilla's Firefox codebase that tends to specialize in providing social networking and Web 2.0 facilities built into its user interface.

Flock 2.0 integrates social networking and media services including MySpace,[2] Facebook, YouTube, Twitter, Flickr, Blogger, Gmail, Yahoo Mail, etc.[3] Notably, when logging into any of the supported social services, Flock can track updates from friends: profiles, uploaded photos, and more.

Other features include:
* native sharing of text, links, photos and videos;
* a "Media Bar" showing preview of online videos and photos as well as subscription to photo and video feeds;
* a feed reader supporting Atom, RSS and Media RSS feeds;
* a blog editor and reader, allowing direct posting into any designated blog;
* a web-mail component allowing users to check supported web-based email off site, compose new messages, and drag-and-drop pictures and videos from the "Media Bar" or webclipboard into a new email message;
* support for third-party add-ons, including a number of Firefox extensions.