Micro-blogging - also known as micro-updating or micro-sharing - allows individuals to keep in constant touch with one another. A micro-blogging service lets you write brief text updates (of up to 140 characters) and broadcast them. People then sign up to follow your messages and you can sign up to follow others and receive their messages.

Micro-blogging tools and services

There are a number of micro-blogging services including:

Twitter - a public service (read about Twitter on our wiki here)
Yammer - a private service
Edmodo & StatusNet - Edmodo is an educational service and StatusNet an open source service
Socialtext - Signals being the service with this enterprise collaboration platform
Yarnable - A public discussion based service (This was started by Ahmad Mukoshy (http://www.ahmadmukoshy.com, http://twitter.com/mukoshy . Read our interview with him here)