Features and Capabilities:

This is only a very quickly thrown together list of GIMP features.

• Painting
° Full suite of painting tools including Brush, Pencil, Airbrush, Clone, etc.
° Sub-pixel sampling for all paint tools for high quality anti-aliasing
° Extremely powerful gradient editor and blend tool
° Supports custom brushes and patterns
• System
° Tile based memory management so image size is limited only by available disk space
° Virtually unlimited number of images open at one time
• Advanced Manipulation
° Full alpha channel support
° Layers and channels
° Multiple Undo/Redo (limited only by diskspace)
° Editable text layers
° Transformation tools including rotate, scale, shear and flip
° Selection tools including rectangle, ellipse, free, fuzzy and intelligent
° Advanced path tool doing bezier and polygonal selections.
° Transformable paths, transformable selections.
° Quickmask to paint a selection.
• Extensible
° A Procedural Database for calling internal GIMP functions from external programs as in Script-fu
° Advanced scripting capabilities (Scheme, Python, Perl)
° Plug-ins which allow for the easy addition of new file formats and new effect filters
° Over 100 plug-ins already available
• Animation
° Load and save animations in a convenient frame-as-layer format
° MNG support
° Frame Navigator (in GAP, the GIMP Animation Package)
° Onion Skin (in GAP, the GIMP Animation Package)
° Bluebox (in GAP, the GIMP Animation Package)
• File Handling
° File formats supported include bmp, gif, jpeg, mng, pcx, pdf, png, ps, psd, svg, tiff, tga, xpm, and many others
° Load, display, convert, save to many file formats
° SVG path import/export
• Much, much more!

Homepage - http://www.gimp.org/