Many new handsets feature displays that refresh up to 120 times per second. You can imagine just how much battery life must be consumed in order to power such a feature. Some Android phones use variable refresh rates based on the content that appears on the screen.
Applications that can benefit from the higher refresh rate, such as games, will update on the screen at 120Hz; other apps that don’t benefit from the faster refresh rate, like texting, for example, will reduce the refresh rate to a much lower number. In other words, the refresh rate is based on the app being used.