From Seo Wiki - Search Engine Optimization and Programming Languages
Yahoo! Toolbar is a toolbar that installs on the Internet Explorer and Firefox browsers, within the context of internet access functions. It allows access to several functions, including Yahoo! Search and Yahoo! Mail. It also contains built-in algorithms to prevent pop-ups and spyware. Several additional features are available on the Internet Explorer version, as well as incorporating Firefox-style tabbed browsing to IE version 6.0 (versions 7.0 and later allow tabbed browsing).
To install, users must have the following requirements:
Mac and Linux users
Opera and Safari are currently not supported.