Yahoo has introduced a mechanism for external developers to give their web applications access to data that Yahoo members have stored in Yahoo services.

Yahoo made available the protocol that provides this bridge, called Browser Based Authentication, last week. It works with two Yahoo services, Yahoo Mail and Yahoo Photos, with support for other services planned for the next few months.

The protocol requires that users give their authorisation prior to giving third-party web applications access to their Yahoo data. Developers also need to register their applications with Yahoo.

The idea behind Browser Based Authentication is to extend the popular 'mashups' of Yahoo web services with external applications by bringing personal user data, such as stored email messages and photos, into the mix.

Providing access to this data will allow Yahoo members to use external web applications in ways that haven't been possible before. Until now, this data has been kept out of the reach of non-Yahoo developers.

For example, external developers can now write applications that allow Yahoo users to perform actions on their email messages or photos that Yahoo hasn't come up with. Yahoo wants to tap into the creativity of external developers who can broaden the scope of tools, applications and features available for its online services.

More information can be found here.