What is the full form of mAh

mAh: milliampere-hour

mAh stands for milliampere-hour. An ampere-hour or amp-hour (Ah) is a unit for measuring electric power over time.

The milliampere-hour (mAh) is one-thousandth of an ampere-hour. mAh is commonly used to describe the total amount of energy a battery can store at one time.

As an example, using higher mAh batteries in a device with constant electrical consumption will theoretically give you longer operating times.

Technically, a higher mAh rating means the (fully-charged) battery can power a device that consumes more power and/or for a longer amount of time before becoming depleted and needing to be re-charged.