How Processes Communicate

Program vs. Process vs. Thread

We’ve loosely used the term ‘process’ pretty much interchangeably with the term ‘application’ in the last few chapters. Now, let’s now get a finer definition.

• A program is simply an executable file. An application such as MS Word is one example.
• A process is any currently running instance of a program. So one program can have several copies of it running at once. One MS Word program can have multiple open windows.
• A thread is a lightweight process. One process can have multiple running threads. The difference between threads and processes is that threads do lightweight singular jobs.

Here’s the MS Word example illustrated: