To many this might seem like an odd question. I mean it’s pretty easy to see if your mail program or word processor is running, right? Well, yes. But there’s so much more you don’t see. Today’s operating systems are quite complex and doing nothing your machine might have a dozen different processes running.
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In the Windows 9x world (Windows 95, 98 and Me), CTRL+ALT+DEL brings up a dialog box that lists almost all of the processes running. I say almost because portions of the operating system itself might not be represented. That’s by design since in Win 9x that dialog isn’t really there to give you information but rather to allow you to terminate unresponsive programs.
In Windows XP (and its predecessors Windows 2000 and Windows NT) the system includes a built in “Task Manager”. There are many ways to run it, but my favorite shortcut is to right click on the clock in the task bar and select “Task Manager”. It too will show you a list of applications running which may be very short much like under Windows 98. However under the Processes tab you’ll find a list of all processes running on your machine – there will be many more, especially if you select the Show processes from all users checkbox. (Hint: you can click on the columns in Task Manager to sort the output by that column which is particularly handy when you want to see who’s using the most memory or CPU time.)
Given the difference in size between the list of applications running and the list of processes running it begs questions like “Why?” And “What’s that difference between the two?”.
A simple answer is this: a process is a single running program and an an application consists of one or more processes. If you’ve got Microsoft Word running you’ll see “Microsoft Word” in the application list and winword.exe in the process list. All those other processes? In a sense they’re running as part of the operating system “application”.
But what are they? Well that’s going to vary a lot from machine to machine based on two things: the software installed and the hardware installed. Certainly obvious items might include your instant messaging client, or other programs you use and know about. However when you install some software packages they may cause additional processes to run on your machine even when you’re not running the application. Examples include Real Player or QuickTime’s update services, a fax program’s receive monitor, or a virus scanner’s real-time virus scanning process. The same applies for hardware, many hardware drivers include additional processes that run all the time.
There’s no one answer for determining exactly what each process running on your machine is, however I do cover many of the steps you can take to figure it out in this previous article: What’s this program running on my machine?.