Two kinds of batteries are widely available: Ni-CD (Nickel Cadmium) and Ni-MH (Nickel-Metal Hydride). There is a third type of rechargeable battery, Lithium Ion, that is becoming increasingly popular.The advantage of a Lithium Ion battery is that it offers better performance than the other two types. The disadvantage is that they do not come in the standard AA battery size, so you can't use them with most cameras.