Photoshop is an image editing application that has a wide range of tools and commands that alter an image digitally. Photoshop uses bitmap images for editing. A bit map image consists of a rectangular grid, called a raster, which is made up of pixels or dots of colour; the image is like a digital mosaic. When editing a bitmap, you are editing the colour the colour values of each individual pixel.
Photoshop can be used for a variety of reasons. For instance, it can be used to edit colour, retouching, correcting red eye and other mistakes and for compositing. It can also be used creatively in the field of graphic arts to create visually attractive images. It can also be used to alter images for advertising or publication. Photoshop can be used by professionals and amateurs alike. There are many free Photoshop tutorials and forums available online for both the beginner and more advanced user.

 This software is very popular in the designer community because of its stunning and new features with the help of which designer can made beautiful graphics very quickly.
It is very good software for changing digital images or making own graphics.

Photo shop is compatible with many operating systems like MAC ,windows any version and the new version of Photo shop 10.0 can even run on the Linux using some software. The images made in the Photo shop are used increasingly for the web.

In Photo shop you can use many colours adjustments like RGB, CMYK, Gray scale, Bitmap, Duotone and Lab colours.
There is much more facilities in the filter option to enhance our digital image or any image.
Photo shop is best for making web graphics like banners, templates, and also can make the interactive menus and many more things. There is also the facility of making website of your photo gallery.
With the passage of time there come many new plug ins for Photo shop which have good features for use.
Well simply I would say that Photo shop has given the revolution to the digital photography.
Photo shop can edit many file formats like jpg ,gif ,bmp ,and can also edit fireworks formats.
Its default saving format is .psd .