Apart from all the functions of an Internet Instant messenger that Yahoo Messenger has been performing over the years, now with this version you can make calls through the messenger. The improvements do not stop there.
The Yahoo Messenger allows for customized stealth settings, and status messages. You can share files up to the size of 2GB, and also share videos. Sharing happens in real time and it does not therefore affect your messenger chat or voice calls. You can chat with one or start conversation with a group.

Yahoo Messenger supports phone calls for free from PC to Phone or send an SMS, there is also the option to call PC-to-PC. With emoticons that can work both in chat window to your status messages, along with IMVironments and Avatars you can create your own theme for the chat experience. If Yahoo Messenger is security that you are worried about then if you have Norton Antivirus or Internet Security  2007/2008 you are automatically protected from any malware that may enter through the messenger. However what happens to the users who do not have these systems of protection is still a question.