Twitter’s premise (and logo) is likened to the constant “tweeting” of friendly birds, updating each other with their surroundings.  This website allows the user to create a list of contacts and then update these people constantly throughout the day by answering the question, “What are you doing?”
Twitter can be used as a powerful learning tool, effortlessly connecting the classroom with the wider community.  Parents can join in classroom discussions.  Students can communicate their learning with peers from other schools.  Distance no longer is an issue, Twitter allows you to instantly share bursts of on-the-spot news with any willing followers to your classroom.
Twitter is a fun, engaging technological tool that encourages controlled interaction with the outside world at any moment of any day.  Parents get a real buzz out of hearing news from the classroom as it happens, since it allows them to discuss with clarity the events that unfolded during the day.  You can even connect Twitter to mobile phones, allowing followers to receive updates from your classroom on the go!
Twitter is a must-use website for any teacher that wishes to activate effortless interaction with a wide network of specifically selected edu-buddies, who will eagerly partake in (whether they realise it or not)  the collaborative learning that occurs naturally within your classroom.

To learn more about Twitter and how you can set up an account for you classroom click here for you free guide.

Common Craft have also produced a great video explaining twitter in simple terms.

Here are some links that are more specific to using twitter in education.

Twenty-One Interesting Ways To Use Twitter In The Classroom by Tom Barrett

100 Tips, Apps and Resources for Teachers on Twitter – A good list of resources and links.