The Raspberry Pi Camera Module is an official Raspberry Pi accessory that works with all models of the Pi, and can be used to take high-definition stills and video images. It connects directly to the Pi board's camera serial interface (CSI) port, which is dedicated to these modules to enable high-speed operation.
The camera itself is a 5 megapixel fixed-focus sensor supporting 1080p, 720p, and VGA video modes and still captures.
You can also obtain housings for the camera modules, which, unless you're going to build your own enclosure for the camera system, I recommend you use.