Difference between multitasking, multithreading and multiprogramming

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I was a little confused between these three terms Multitasking, Multithreading and Multiprogramming

Although every one means executing different lines of codes, and for every one we need something like Task State Segment or context to store data for that particular thread/task.

I am missing something, can anyone give me the basic difference between them and how they are actually executed in a processor

Edit: Actually I was a guy from Electronics background and I was poor at OS related issues. The main thing I understood between multiprogramming and multithreading is that in multiprogramming we execute two separate programs where as in multithreading the scheduler produces two different threads which can be executed independently. I think these are a form of multitasking implementation. Am I correct. I was really confused

Asked By : sai kiran grandhi

Best Answer from StackOverflow

Question Source : http://cs.stackexchange.com/questions/18728

Answered By : David Richerby

The Wikipedia article Computer multitasking covers this well. In summary:

• Multitasking: there is more than one process and the operating system somehow decides which to run next.
• Multithreading: threads are essentially subprocesses, which share memory (separate processes cannot normally access each other's memory) but which are independently scheduled.
• Multiprogramming: a form of multitasking in which a process keeps running until it tries to access an I/O device, at which point another process is chosen to run so the CPU doesn't idle waiting for a punched card reader or something.