Yahoo Messenger is a free service that allows you to see when friends come online and to send them instant messages. It also can alert you to new e-mail in your Yahoo Mail or Yahoo Personals accounts, or when you have upcoming events recorded in your Yahoo Calendar.

Yahoo Messenger offers firewall support, a standby mode that minimizes the program until an Internet connection is made, the ability to save and print your conversations, and a tabbed interface that provides quick access to your favorite stocks, news, and sports scores.

Other features include the ability to create a chat room automatically, stock price alerts, the ability to send messages to friends (even if they're not online when you are), a Quick Compact mode that hides the Messenger tools to maximize your viewing area, Messenger Themes, and voice chat, which allows you to talk for free to anybody else on the Internet.

It also includes Launchcast Radio, Yahoo Games, and Yahoo Audibles. Using a Webcam, you can see who you're chatting with or view the Webcam of any Yahoo member who has granted you access.

The latest release of version 8.1 is a highly critical security fix that plugs a hole where an attacker could take over you computer.