Yahoo! Messenger is very popular, because it allows you to chat and call friends instantly and for free. You can spice up your conversations with various smiley emoticons. As long as you have a webcam, you can video chat with one another, making distant friends seem closer than ever. If your loved one isn't available to chat when you are, you can even drop them a voice message to come back to.
Note: Yahoo Messenger has been discontinued since July, 17 2018. For more information, see this page.