Task vs. process, is there really any difference?

Question

I'm studying for my final exams in my CS major on the subject distributed systems and operating systems.

I'm in the need for a good definition for the terms task, process and threads. So far I'm confident that a process is the representation of running (or suspended, but initiated) program with its own memory, program counter, registers, stack, etc (process control block). Processes can run threads which share memory, so that communication via shared memory is possible in contrast to processes which have to communicate via IPC.

But what's the difference between tasks and process. I often read that they're interchangable and that the term task isn't used anymore. Is that really true?

Answer 1

The term "task" is mostly used in the context of scheduling*, when it can refer to either a thread or a *process***, that can be scheduled to run on a processor.
From the scheduler's point of view there might be little-to-no difference between a thread and a process - both represent a task that must be scheduled.

Recently, the term "task" is gaining more-widespread usage, especially among .NET developers, thanks to e.g. the Task Parallel Library. Within it, tasks are units of work that can be scheduled to run on threads from a pool of worker threads.

_{* e.g in kernel programming, esp. on Linux
** theoretically, you could make up your schedulable entities}