Although primarily designed to edit images for paper-based printing, Photoshop is used increasingly to produce images for the World Wide Web. Photoshop also has strong ties with other Adobe software for media editing, animation and authoring. Files in Photoshop's native format, .PSD, can be exported to and from Adobe ImageReady, Adobe Illustrator, Adobe Premiere Pro, After Effects and Adobe Encore DVD to make professional standard DVDs, provide non-linear editing and special effects services such as backgrounds, textures and so on for television, film and the Web.
Photoshop can deal with a number of different color models such RGB color model, Lab color model, CMYK color model, Grayscale, Bitmap and Duotone. The PSD (Photoshop Document) format stores an image as a set of layers, including text, masks, opacity, blend modes, color channels, alpha channels, Clipping paths, and duotone settings.
The official website for Adobe Photoshop :
http://www.adobe.com/products/photoshop/photoshop/
The trial version of Adobe Photoshop can be downloaded from following site for free :
http://www.download.com/Adobe-Photoshop/3000-2192_4-10011172.html
For tutorials click following links :
http://www.tutorialized.com/tutorials/Photoshop/1
http://www.good-tutorials.com/
http://www.good-tutorials.com/