Sensor sizes

Sensor sizes can vary across camera types and even across DSLRs. Point-and-shoot cameras typically have quite small sensors. Most DSLRs have larger sensors. They are called APS-C or "cropped" frame sensors because their surface area is smaller than a 35 mm film frame. Some DSLRs have "full frame" sensors that are approximately the same size as a 35 mm film frame. There are even much larger medium format sensors.

There are advantages and disadvantages to having full frame sensors to cropped frame sensors. Full frame sensors can provide more resolution or larger photosites. More resolution generally means better capability for very large prints. Larger photosites generally means lower noise. On the other hand, cropped sensors can be advantageous when additional reach is needed with lenses, such as for sports or wildlife photography.

Currently, prosumers have several choices between full frame and cropped frame cameras. Professionals have been steadily moving to full frame, though some remain with cropped frame cameras because of the advantages stated above.

The article linked below provides a laundry list of other considerations.


Links:
http://www.cambridgeincolour.com/tutorials/digital-camera-sensor-size.htm