Raspberry pi is one of the most popular SBC in market with ARM processor. It is very popular among students for playing as embedded stuff.
There are few points, need to noted down, while working or playing with Raspberry pi.
1. SDCard shows 56 MB, while I've 4 / 8 / 16 GB etc.
The reason, windows cannot read the actual size of SDCard is, its reading only the boot partition. To get rid of this problem, its advised to use SDFormatter.
2. Which image to Install ?
Default Raspberry pi gives two type of installation image.
1. NOOB -- completely for beginner. I'd say for those who have no / less knowledge about linux.
2. Raspbian -- A good place to start learning with Raspberry pi. Usually WHEEZY image is popular as starting. If you've smaller SDCard, and no requirement of Desktop, you may choose Jessie Lite minimum version.