Instant water heaters, also known as tankless water heaters, provide hot water on demand without the need for a storage tank. They heat water directly as it flows through the unit, ensuring a continuous supply of hot water whenever needed. This makes them energy-efficient, as they only use energy when hot water is required. These devices are compact and can be installed in various locations, such as under sinks or in utility rooms. Instant water heaters are popular in both residential and commercial settings, offering convenience and reducing the risk of running out of hot water during peak usage times.