There are many kind of microcontrollers out there, some are just plain simple and some are really sophisticated-kind of controller. The one that I'll be using for most of my project can be both, depends on how you using it.
So guys, this is the Arduino, the open-source electronic prototyping platform (just as it says in the official site :-P ). This means that it is a single-board integrated microcontroller unit with lot of features. Arduino was born in Italy by a group of brilliant guys who's experimenting with physical computing.
I will not explaining every detail about this Arduino thing. You can read it in their website. Its a good place to start for every beginners to explore the wonderful world of Arduino. They provide very detail explanation and step-by-step guide for anyone who interested to start with Arduino. I really like their playground site, kind of wiki to Arduino. Here you can find a lot of information for everything about Arduino and this is the place where the Arduino community sharing their ideas and work. Recommended place to go if you want to get your hand on Arduino. It really helps me a lot.
By the way, as you can see in the picture above, it is an Arduino-clone board actually, which I bought it from China for only USD 20 (through eBay, of course) :-P ...Obviously you can't see the 'Arduino Duemilanove' and 'Made In Italy' or even the 'www.arduino.cc' words printed on the board (here is the original board). But because of its open-source license, it is not illegal to clone the Arduino board. Most important to me, it is cheap and works just like the original board 'Made In Italy'... Haha!
Lastly, I just want to show you guys how small this Arduino board is. As you can see, it is smaller than a size of standard credit card. Damn! It is small.. Haha!