GIMP is an acronym for GNU Image Manipulation Program. This is a free open-source image editing program for Unix, Windows or Macintosh.
You can pretty much accomplish all the basic editing tasks as you can with expensive software.
Do not get GIMP confused with cheap image software packages that come with your printer or camera. GIMP is a very popular and respected program.
Being a cross-OS program, you can easily collaborate your projects with others, even if they use a different Operating System. You can tell someone to click the triangle tooltip third from the left to make the edit, and the exact same tooltip third from the left will be on their screen as well no matter if they use Windows, Macintosh or Linux.
Remember to go to File > New... when you first use the program. Otherwise, you'll wonder why you can't draw on the blank space. The program may seem confusing at first, but all those windows are there to maximize your space while you edit or draw. Basically, if you need to, you can just maximize the main window for the most working area possible.
After unzipping the ZIP for the required GTK installer, and trying to run the install, I got the following error (Damn technology):
Previous installation of GTK+ 2 runtime environmet was detected, however the Setup could not find the uninstaller required to uninstall it automatically. Please uninstall it manually before running the Setup again.
This isn't too big of an issue since I was able to find a version of GTK+ in my Windows Control Panel with the message, "(remove only)", which is exactly what the GTK installation wants me to do. You may need to do the same thing. In retrospect, I probably didn't need to download another GTK at all anyways since I already had a fairly new one.
After you have a new version of GTK, you can simply download GIMP and install it. If you are confused on how to get this program, ask someone to help you install it. If you are on your own, make sure you select either GIMP for Unix, GIMP for Windows, or GIMP for MacOSX to begin.