GIMP is an image manipulation and editor program that was released first time in 1996 in U.S. is an open source program available for all major platforms and allows photo manipulation and retouching.
Is working with all popular image formats: PNG, JPEG, GIF, TIFF, SVG, PSD (allows to import and work with files created by Photoshop) and more. Includes various tools for painting, supports layers and channels, unlimited undo and redo, selection tool in different shapes, allows scripting and animation. Often is considered the main alternative to Adobe Photoshop.
This application allows professional editing and image creation or modification.