An AA battery is a standard size of cylindrical battery commonly used in various electronic devices. It typically measures about 50.5 mm in length and 14.5 mm in diameter. AA batteries can be found in two main types: alkaline and rechargeable NiMH (nickel-metal hydride). They provide a voltage of 1.5 volts for alkaline and 1.2 volts for rechargeable versions. These batteries power a wide range of devices, including remote controls, flashlights, and toys. Due to their popularity, AA batteries are widely available and often sold in packs. Their versatility and ease of use make them a common choice for everyday electronics.