The Yahoo Open Strategy, also referred to as Y!OS, is search engine Yahoo!'s initiative to make users' personal information available to them throughout Yahoo!'s various services. CTO Ari Balogh announced the new initiative at the 2008 Web 2.0 Expo. On October 16, 2008 Yahoo! rolled out new user profiles, the first product release for the social side of the Y!OS. The new profiles allow users to connect with friends, and include an activity stream which will integrate with other Yahoo! products and services.TechCrunch: Go Get Yer Shiny New Yahoo Profile... (October 16, 2008)

Though the focus of Y!OS is integration, Balogh noted that Yahoo is not planning to launch or become a social networking site. Rather, social components are being added to all Yahoo! sites, beginning with Yahoo's new user profiles.

Another component of the open strategy is to allow third-party developers to create applications that will run on Yahoo! sites. The feature is similar to MySpace's MySpace Developer Platform.