Four types of operating system

1. Windows: Developed by Microsoft, Windows is one of the most widely used operating systems for personal computers. It is known for its user-friendly interface and compatibility with various software applications.

2. macOS: Developed by Apple Inc., macOS is the operating system used on Apple's Macintosh computers. It is known for its sleek design, security features, and integration with other Apple devices.

3. Linux: Linux is an open-source operating system that is widely used in servers, supercomputers, and mobile devices. It is known for its stability, security, and customization options.

4. Android: Developed by Google, Android is a popular operating system used on mobile devices such as smartphones and tablets. It is known for its user-friendly interface, extensive app store, and customization options.