GIMP is an acronym for GNU Image Manipulation Program. It is a cross-platform image editor available for GNU/Linux, OS X, Windows, and more operating systems. It is free software, you can change its source code and distribute your changes.
Whether you are a graphic designer, photographer, illustrator, or scientist, GIMP provides you with sophisticated tools to get your job done. You can further enhance your productivity with GIMP thanks to many customization options and 3rd party plugins.
GIMP is an excellent free alternative for Adobe Photoshop, with a familiar interface yet slightly different learning curve.