What's a tweet?

Now, I have never used twitter, but I still see no relevance or significance of the name Twitter. In fact, the entire idea of Twitter seems completely ridiculous to me. I can only imagine why the creator of Twitter decided to give it such an absurd name, especially when the correct term for posting something on Twitter is referred to as a "Tweet". I could discuss all of the recent internet phenomena for literally hours, but I will leave it at the fact that Twitter is like no other, in that it serves no real purpose.