Well I have found this while surfing flickr, CEO Jack Dorsey is the actual creator of the Twitter and CFO is Evan Williams. This sketch that reveals the original idea that led to the birth of Twitter. His concept of this first think was really appreciative because, I know twitter as updating a status of 140 words and more over a share of articles but never heard the use or original idea of twitter from the Creator itself.
The main concept or so called definition of twitter from his lines:
"I had an idea to make a more "live" LiveJournal. Real-time, up-to-date, from the road. Akin to updating your AIM status from wherever you are, and sharing it. For the next 5 years, I thought about this concept and tried to silently introduce it into my various projects. It slipped into my dispatch work. It slipped into my networks of medical devices. It slipped into an idea for a frictionless service market. It was everywhere I looked: a wonderful abstraction which was easy to implement and understand.We're calling it twttr (though this original rendering calls it stat.us; I love the word.ed domains, e.g. gu.st/)"
Well a small idea has become a big and then bigger...
Just observe the picture for a few moments, his first idea seems to be like just updating and learning.