What is thread?

• Threads are subsets of a process. You may also call it as a light weight process.
• Multiple threads can exists in same process.
• In single processor system, the threads are executed as time-division multiplexing. The process time is divided into equal times for the thread and Operating system will switch between the threads as soon the time slice is over for the thread. Then it will resume as soon as it gets the time slice again. Physically the threads are executed sequentially but the user experience as multi tasking happens at the background.
• In multiprocessor system, the threads are distributed across processors so the threads are simultaneously.