Adobe Photoshop is not free, however, you can download a fully-functional 30-day tryout version of Photoshop from Adobe.com. If you wish to continue using the software after the free trial period, you will need to purchase it.
If the cost of Photoshop is too much for you, consider Photoshop Elements instead. Photoshop Elements offers about 99% of the functionality of Photoshop at about a sixth of the price, and was designed to meet the needs of most non-professionals who will never use many of Photoshop's advanced features. A free 30-day trial version of Photoshop Elements is also available for download from Adobe.
In March of 2008, Adobe announced Photoshop Express, a free online service for storing, sorting, editing, and showing off digital photos. Although it is not as rich in features as the desktop software Photoshop and Photoshop Elements, it is a legitimately free way to use Adobe Photoshop technology.
In addition, there are many very good photo editing programs that are free and offer many of the same features of Photoshop. To learn more, browse the free graphics software section of this site, or visit the following links for my top picks.