Yahoo! Groups is a communication tool provided by Yahoo that allows users to participate in online forums and mailing lists. It is important for users to read the Yahoo! Groups terms of service (TOS) which outlines important policies regarding content ownership, privacy, and data sharing. The TOS explains that Yahoo! may share user information with partners and uses cookies for advertising. It also covers Yahoo's monitoring of content for inappropriate language, protections for children's accounts, and banning of pornography.