A tank water heater is a common appliance used to heat and store water for residential and commercial use. It consists of a large insulated tank that holds a specific volume of water, typically ranging from 20 to 80 gallons. The heater warms the water using either electricity or gas, ensuring a steady supply for activities like showering, washing dishes, and laundry. When hot water is needed, it is drawn from the top of the tank, while cold water enters the bottom to be heated. These heaters are known for their reliability and ability to provide hot water on demand, although they can take time to refill and reheat after heavy use.