“Twitter is a social networking and micro-blogging service that allows its users to send and read other users' updates (known as tweets), which are text-based posts of up to 140 characters in length.”
Now a bit of a disclaimer here. There are hundreds of manuals about Twitter and how best to use it and no one agrees on what is best. Here I am looking only at how you can use this to improve and leverage your blogging efforts.
Twitter can be used for much more than that but that is not our topic here.
So we have the Wikipedia definition and here is my take on it and what a blogger needs to know and use.
Twitter is a micro blog platform. You are limited to 140 characters per post. This forces you to be concise and keep each tweet (Twitter post) to just one topic.
The key to effectively using Twitter is to understand that it is a conversation between people. It is about sharing information. It is not a sales platform although some will disagree with that. I am not saying that you can't use it to sell but you need to do it the right way.