Photoshop is a bitmap graphics editor, published by Adobe. It is the market leader for commercial bitmap image manipulation. As with most of other Adobe's applications, Photoshop is available for Mac OS and Microsoft Windows. It has also been released for Unix.
The development of Photoshop started in 1987 by the brothers Thomas and John Knoll, although it was not until 1990 that the program was first released by Adobe. The program was intended from the start as a tool for manipulating images that were digitized by a scanner, which was a rare and expensive device in those days.
Although primarily designed to edit images for paper-based printing, Photoshop is used increasingly to produce images for the World Wide Web. Recent versions have been shipped with a separate application, ImageReady, which provides a more specialised set of tools for this purpose.
The term photoshopping is a neologism, meaning 'editing an image,' regardless of the program used. Adobe discourages use of the term out of fear that it will undermine the company's trademark. It is sometimes used with a derogatary intent by artists to refer to images that have been retouched instead of originally produced. A common issue amongst users of all skill levels is the ability to avoid in one's work what is referred to as "the Photoshop look" (although such an issue is intrinsic to many graphics programs).
Photoshop is generally considered one of the best (if not the best) image editing programs. Its main disadvantage is its hefty price; in that way, it is similar to 3D Studio Max: it is one of the best programs, but it is not the most popular, because of its price. This has allowed competing programs such as Jasc Software's Paint Shop Pro and The GIMP Team's GIMP to become popular. To capture this lost market share, Adobe has introduced a much less expensive program called Photoshop Elements that consists of Photoshop minus some of the high-end output capabilities, useful for editing photos from consumer digital cameras and for doctoring images for the web but not as useful for professional prepress work.