While a traditional water heater will continuously store and heat your home's water throughout the day, a tankless water heater heats your water on demand. Tankless water heaters have become more popular due to their increased efficiency and convenience; you never have to worry about running out of hot water if you have multiple members of the household showering consecutively.
A current caveat to tankless water heaters is their larger upfront costs for installation, however this is consistently changing as the increased demand drives down the price. And it's important to remember that while tank water heaters deteriorate over time, often suffering from internal mineral buildup and petering out after six to eight years, tankless water heaters can last up to 20 years with minimal maintenance; providing a great return on investment.