Surprised? Without a source of power, cameras can't perform. Batteries come in all sizes and shapes. What you are familiar with is the AA or AAA like the one pictured here on the right.
The best batteries are Lithium as they last the longest. The minimum requirement for cameras is alkaline. Ordinary ones just won't do. There are also rechargeable AA and AAA batteries. Get the highest mAh rating you can afford not going lower than 2000 mAh for AA.
Some batteries are propriety, meaning the manufacturers have made their own standard for exclusive use in their cameras. This is done to ensure a slimmer camera form. They are still batteries and have to be recharged using the supplied wall charger. Most camera batteries can not be recharged through the USB slot of a computer.
Now you know!