The three types of operating systems are:

1.  Single user operating sytems:

Single user operating systems allows only one user to share the system resources including the CPU. For example, DOS (disk operating system).

2. Batch operating system:

In a batch processing operating system interaction between the user and processor is limited or there is no interaction at all during the execution of work. Data and programs that need to be processed are bundled and collected as a ‘batch’ and • executed together.

For example, IBM OS/2.

3. Multi tasking operating system:

In multi tasking operating system several applications maybe simultaneously loaded and used in the memory. While the processor handles only one application at a particular time and switch between the applications and simultaneously execute each application.

For example, Windows operating system.

4. Multi user operating system:

This multi user operating system allows multiple users to simultaneously use the system, the processor splits its resources and handles one user at a time.

For example, UNIX.