GIMP (GNU Image Manipulation Program) is a free and open-source raster graphics editor used for photo retouching, image editing, and digital painting, serving as a powerful alternative to proprietary software. Originally released in 1996, GIMP has evolved into a professional-grade tool supporting advanced features like layer management, non-destructive editing, and extensive plugin architecture. Understanding GIMP's tool paradigm is essential: unlike simpler editors, GIMP separates transformation from selection, treats channels as first-class objects, and builds complex effects through layer composition—mastering this mental model unlocks the full power of its seemingly overwhelming interface.