Single- and multi-tasking :
A single-tasking system can only run one program at a time. A multitasking operating system can run more than one program at the same time. Multi-tasking is done by dividing processor time. The processor gives a little bit of its time to each program.
Single- and multi-user :
Single-user operating systems cannot distinguish between users, but may allow multiple programs to run simultaneously. A multi-user operating system permits multiple users to interact with the system at the same time.
Distributed :
A distributed operating system manages a group of distinct computers and makes them appear to be a single computer. Distributed computations are carried out on more than one machine.
Templated :
In an OS, distributed and cloud computing context, templating refers to creating a single virtual machine as a guest operating system, then saving it as a tool for multiple running virtual machines. The technique is common in large server warehouses.
Embedded :
Embedded operating systems are designed to be used in embedded computer systems. They are designed to operate on small machines like PDAs with less autonomy and are able to operate with a limited number of resources. Windows CE and Minix 3 are some examples of embedded operating systems.
Real-time :
A real-time operating system guarantees processing of events or data by a specific moment in time. A real-time operating system may be single- or multi-tasking, but when multitasking, it uses specialized scheduling algorithms so that a deterministic nature of behavior is achieved. An event-driven system switches between tasks based on their priorities or external events while time-sharing operating systems switch tasks based on clock interrupts.
Library :
A library operating system is one in which the services that a typical operating system provides, such as networking, are provided in the form of libraries and composed with the application and configuration code to construct a unikernel: a specialized, single address space, machine image that can be deployed to cloud or embedded environments.
