Yahoo! Messenger is a program for sending instant messages online through the Yahoo! system. The requirement for usage of Yahoo! Messenger is a Yahoo! email account and the requisite software.

Yahoo! Messenger is available for the following platforms:
Though the protocol used by Yahoo! Messenger is closed, Yahoo! has been among the vocal competitors to AOL/Time-Warner's AOL Instant Messenger, because of the fact that the AIM protocol is closed and blocks non-AIM clients from connecting. The downside to this is that a user with Yahoo! Messenger cannot contact a user with AOL Instant Messenger. Yahoo! has sought remedies to allow the clients to interact, though has in the past blocked other clients from using its service.

In addition to being an IM client, Yahoo! Messenger provides up-to-the-second updates on new email arriving in the user's inbox (for Yahoo! mail only, though), includes a search engine frontend, and allows stock updates.

The client is small and unobtrusive, especially when compared to AOL Instant Messenger, MSN Messenger, and most of all, ICQ. It has a complete array of options without being egregious.

Yahoo! Messenger is available at An alternative client, for connecting to not only Yahoo!, but IRC, ICQ, AIM, and MSN, is available at