Throughout the course of Windows history, one process has always stood out to me the most. It runs silently in your task manager, calmly taking up memory with little explanation as to what it does. Of course, I’m speaking of rundll32.exe. In fact, you may have seen it crop up a time or two when a program crashes, but other than that, it’s just something that is “there”.
So what is it, exactly?
Well, Rundll32 is actually a medium for which other DLL files  go through. Think of it like a baseball pitching machine, and the DLL files are the baseballs. Since there is no way to directly launch a DLL file by itself, Windows needs an application to do this. That’s where rundll32.exe comes in. It launches functionality stored within 32 bit DLL files, thus the name, “run dll 32”.
Be warned, however, as malicious programs like spyware can run under the same name! Keep your virus scanning software up to date, and run weekly spyware checks! That way, you’ll ensure that the process you’ve just learned about is the one with good intentions!