Adobe Photoshop is a powerful graphics editing program developed by Adobe Systems. It has been the market leader since 1992 and supports Macintosh and Windows platforms. Key releases include Photoshop 2.5 which introduced layers, Photoshop 5.0 which added the history palette for undo functions, and Photoshop CS3 and CS4 which improved the user interface, added new editing tools like smart filters, and enhanced compatibility with other Adobe software. Photoshop remains the flagship product of Adobe Systems for bitmap image editing.