A camera bag is smart to have if you want to take care of your camera. There are small cases for protection of compact cameras and mirrorless interchangable-lens cameras (MILC), or big bags for storing your SLR camera, lenses and accessories.
Most manufacturers like Canon, Nikon, Sony and Panasonic make camera bags for their own products. The Lowepro brand makes universal bags with many different options that suit most cameras.
The small cases for a mirrorless interchangable-lens or compact camera fit into the pocket, while the slightly bigger bags are available with handles or as a backpack. Some bags are even so big that they are available as a roller case.