Some of the categories of OS are general purpose OS, mobile OS, real-time OS, and so on.
General-Purpose OS: These operating systems work on process or thread and hardware management so that multiple applications can share the existing devices. Many desktop computers and laptops operate on these OS such as Windows, Unix/Linux, Mac OS, and so on.
Mobile OS: These are designed to accomplish mobile computing such that multiple applications can run simultaneously on a small size device. They work on communication-centric devices which emphasize users' demands, efficient performance, and media streaming. The most commonly used mobile OSs are Google Android and Apple iOS.
Real-Time OS: Real-time operating systems are designed for real-world entities who work on time constraints, such as providing signals to motors, actuators, or valves.
Embedded OS: Some widely used devices such as ATMs or point of sale terminals require extremely powerful operating systems capable of handling numerous operations in a short time. They are highly efficient and are capable of handling errors or sudden crashes.
Network OS: The specialized OS is anticipated to establish the interface between various network devices, such as, routers or switches within a LAN. The common examples of network OS are Cisco IOS, ZyNOS, and RouterOS.