The Themes app is a software application designed to customize the appearance of a device's interface. It allows users to choose from a variety of pre-designed themes that can alter the look of their device's operating system, including the wallpaper and themes.

The Themes app is often available on mobile devices such as smartphones and tablets, as well as desktop and laptop computers. It can be a fun way to personalize a device and give it a unique look and feel, and may also help improve user experience by making the interface more visually appealing and easier to navigate.