Yahoo is one of the most popular email services of the whole world thanks to the large amount of people who are registered there.
Yahoo has a messenger called " Yahoo Messenger"; there are a lot of space in the Yahoo inbox, so the users can receive millions and millions of emails; Yahoo has chatrooms too where we can chat with people all over the world; using the messenger service it is possible to: send archives and photos, do videocalls using our web cam and microphone (the speed is very good, compared to other email and messenger (or im = instant messaging services)).
Well, yahoo has a lot of good thinks, and it is very popular. In the Yahoo's webpage we can use many options: answers , games , finance , groups , messenger , online messenger , and so on.
In fact, Yahoo is one of the most complete websites.
There are other very popular sites like yahoo: Hotmail and Google (I added two links to summaries related to these other two email services. These links are in the bottom of this synopsis).