Digital graphics involves pixels, resolution, size, color, color models like RGB and CMYK, and compression of graphics. GIMP is a free and open source graphics editing program that allows users to view, edit, or create new images. It has various tools for selection, painting, transforming, and other image editing tasks. The interface of GIMP includes a main toolbox, layers, transformation tools, and other tools for image editing. Users can open, save, or export images in different formats using GIMP.