There are many types and sizes of batteries, though most are uncommon and used for specific items. The six most common battery sizes include AAA, AA, C, D, 9-volt and 6-volt Lantern battery.
Most batteries fall into one of four main categories: cylindrical, non-cylindrical, button and camera. Cylindrical batteries rank as the most common type of battery, and AAA, AA, C and D batteries are used worldwide for most consumer and household goods, such as flashlights. These batteries are encased in different sizes of cylindrical casing, with positive and negative ends of the battery on different ends of the cylinder.
Non-cylindrical batteries, such as 9-volt and 6-volt batteries, are mostly box shaped and have the positive and negative terminals on the top. Examples of items requiring these types of batteries include smoke alarms, radios and lanterns. Button and camera batteries are more situational. Camera batteries almost exclusively power cameras, but some flashlights require them as well. They usually come in a cylindrical or double-cylindrical shape.
Finally, button batteries power small items, such as watches or LED flashlights, and come in many different diameters and thicknesses. They always, as the name suggests, come in a button shape. Due to their small size, button batteries usually possess less capacity and voltage than their larger, cylindrical counterparts.