Yahoo!Messenger is an instant messenger that lets you stay in touch with other Yahoo! users. It includes features like PC-to-Mobile conversations, emoticons, web cam support, Yahoo! email integration, conference chat file transfers and much more. It also offers stock alerts, calendar integration, news and weather updates as well as an integrated address list and more.

Yahoo! Messenger is a fully featured online communication tool. Its setup integrates the Yahoo! Toolbar which provides anti-spy, pop-up blocker, and quick access to other Yahoo! services (mail, photos, search, etc). With Yahoo! Messenger you can send instant messages, call computers, call a phone number, send a mobile message, or sign in to Yahoo! Mail.
You can edit your current status or change your picture. Its also possible to create your own avatar, which is displayed next to your name in your friends contact list. Sharing your webcam or seeing other people who enable their webcam is easy. If you dont want anyone to see when you are online you should log on using the "Invisible" status. Nobody, except the people you select, would notice you are around. Messages are sent to your friends regardless of their online/offline status. Depending on your network configuration, you should also be able to use this instant messenger for sending files.
During instant messages you have the possibility to customize fonts, send emoticons and audibles, and select IMVironments. Everything is provided for you to have a outstanding time while chatting with your friends. The Inside Yahoo! window provides quick links to news, finance, personals, movies, horoscopes, etc. You also get notifications of new emails and voice messages in this window. If you dont like this feature, you can turn it off from the programs preferences.
In version 8, the "Content Tabs" in the "Preferences" window has been removed. Now "Yahoo! Plug-ins" are available. So far you can install about 15 plug-ins like Music LAUNCHcast, Answers, 360, eBay, iTunes, Amazon.com, Finance, Calendar, Weather, and others. Its easy to stay up to date with new music, movies, sports results, and other stuff that may be of interest to you.
Pluses: On first run, Yahoo! Messenger will look in your Yahoo! Address Book and Microsoft Outlook for new contacts or for people who are using Messenger but are not in your list of contacts. This is done in order to complete your contact list.
The good news is that you can now add any Windows Live Messenger user to your contact list. After installing Yahoo! Messenger, simply click on the link "IM with Windows Live (MSN) Messenger", follow the instructions, and youll be able to chat with Windows Live Messenger users.

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

Here are some key features of "Yahoo Messenger":
LAUNCHcast Radio; Yahoo! Games; IMVironments; Customize your IM window with interactive themed backgrounds. See the IMVironments; Audibles; Emoticons; Yahoo! Avatars; Display Image; Skins; Address Book; Stealth Settings and Privacy
Search; File Transfer; Webcam; Yahoo! Photos; Voice Chat; Conference

Yahoo! Messenger Communication features:
Instant Messaging: Send text messages in real-time to your friends on Yahoo! or Windows Live? Messenger.

Chat Rooms: Join a chat room to meet new friends while you discuss your favorite topics.

Photo Sharing: Share photos from your desktop or Flickr, then discuss them over IM while you and a friend view them together.

PC-to-PC Calls: Make a voice call to another Yahoo! Messenger user for free (microphone and speakers/headset required).
Phone Out (PC-to-Phone Calls): Call friends on their regular or mobile phones from Messenger for as low as 1 a minute (Phone Out account required).
Phone In (Get a Phone Number for Messenger): Get a new phone number that allows you to receive calls in Yahoo! Messenger (Phone In account required).
SMS (Text Messaging): Send text messages from Messenger to your friends mobile phones for free.
Webcam: Plug in your webcam to share live video with your friends on Yahoo! Messenger.
IM Conferencing: Instant message with many friends at once in a conference room (includes voice abilities, where available).
IM with Friends on Other Networks: IM with friends who use Windows Live? Messenger, Reuters Messaging, and Lotus Sametime - right from Yahoo! Messenger.
File Transfer: Send files instantly to a friend while you IM (2 GB limit).

Yahoo! Messenger Productivity Features:
IM Forwarding to Mobile: When you sign out of Messenger, have new IMs sent to your phone as text messages.

Contact Search Bar: Quickly find a contact to IM, call, SMS or more.

Yahoo! Search: Start a web search right from your Yahoo! Messenger window.
Yahoo! Address Book: View and edit your Yahoo! Address Book information for your contacts right from Messenger.
Stealth/Privacy Settings: Make yourself appear online to some friends, and offline to others.
Call Forwarding: Have incoming calls to Messenger forwarded to another phone number, even if you're signed out (Phone Out account required).

Yahoo! Mail alerts: Get notified when new a new Yahoo! Mail message arrives.

Voicemail: When friends call you on Yahoo! Messenger, they can leave you a voicemail if you're unavailable.

Message Archiving: Maintain a private archive of your IM conversations.

Tabbed IM Windows: Reduce desktop clutter by organizing multiple conversations into a single window.

Buzz Alert: Get your friend's attention with a click of the Buzz button.
Yahoo! Updates: Get real-time updates in Yahoo! Messenger about what your friends are posting online, reviewing and generally buzzing about

Yahoo! Messenger Fun & Personalization:
Plug-ins: Add content, services and games to Messenger that you can enjoy on your own, or with friends while you IM.

Audibles: Send an animated, talking character to a friend to liven up your IM conversation.

Emoticons: Express your feelings with these animated, smiling faces.
Avatars: Represent yourself with a stylized, graphic image where you can choose the hair, clothing and more.

Display Images: Display an image to represent yourself to your friends.

Skins: Choose a different skin to give your IM world a new look.

IMVironments: Liven things up with interactive, themed backgrounds in the IM window.

Yahoo! Games: Play a game of pool, backgammon, checkers and more with a friend while you IM.

Custom Status Messages: Tell your friends what you're doing, seeing or feeling by customizing your online status message.

Custom Ringtones: Assign ringtones to different callers, or upload your own audio files to use.

Customizable Fonts & Colors: IM with a font, color and style that suits your personality.

Sound Effects & Soundtrack (During Voice Calls): Throw a sound effect in while you're on a call or upload a music file to play as a soundtrack in the background.

The license of this software is Freeware, you can free download and free use this instant messenger software.