GIMP is a free software raster graphics editor

Raster graphics editor

A raster graphics editor is a computer program that allows users to paint and edit pictures interactively on the computer screen and save them in one of many popular “bitmap” or “raster” formats such as JPEG, PNG, GIF and TIFF....

. It is primarily employed as an image retouching and editing tool and is freely available in versions tailored for most popular operating systems including Microsoft Windows, Apple Mac OS X, and Linux.

In addition to detailed image retouching and free-form drawing, GIMP can accomplish essential image editing tasks such as resizing, editing, and cropping photos, photomontages combining multiple images, and converting between different image formats.