Everybody's heard of Photoshop; it's the world's gold standard when it comes to image editing software. Part of this is due to its age, and part to its capability. The web is a graphical medium, so it makes sense for people who run web sites to have a basic understanding of Photoshop.
There are two "standard" complaints about the application: it has a steep learning curve ( in part because it's so powerful - there are simply "too many" options for new users, who tend to feel overwhelmed ) and its price. In US Dollars, Photoshop CS 3 is $650, while the extended version goes for $1,000. This is mainly of use to people who need to manipulate images in 3D space, or movies on a frame-by-frame basis.
Photoshop Without Photoshop
Because of the high cost, we should start by looking at some alternatives to Photoshop. These run the gamut from open source freeware to closed source commercial applications - the competition - and, ironically, trimmed down versions of Photoshop itself. For the web designer on a budget, some other software to consider is: