There are several mobile operating systems that power smartphones and tablets.
Some of the most common ones include:
1. Android - A popular open-source OS, developed by Google, used on a wide variety of smartphones.
2. iOS - Developed by Apple for use on its iPhone, iPad, and iPod devices.
3. Windows Phone - A now-discontinued mobile OS developed by Microsoft, previously used on Nokia and other devices.
4. HarmonyOS - A new operating system developed by Huawei for its smartphones and IoT devices.