While the use of digital cameras has made it easier for photographers to quickly check whether or not they like the shot they've taken, there are still usually flaws that need to be touched up or a crop that will make the image more dramatic. Because of this, they need to use image editors to produce their desired results.
While image editors that are built-in to the computer's OS (take Microsoft Paint, for example) can do very basic editing, power users such as professionals and web designers need more powerful programs.
There are a number of good image editors out there that are popular among photographers and web designers alike. For one there's Adobe Photoshop.
Ever since it was released in 1990, its use has become an industry standard in the image editing industry. Then there's Corel PHOTO-PAINT of the CorelDRAW Graphics Suite.
This program specifically targets photographers who wish to edit their images using the computer.
Another photo editing software is GIMP which stands for GNU Image Manipulation. The good thing about this photo editor is that you can use it in a variety of operating systems such as Windows, Mac and Linux/Unix.
For those who are used to the Photoshop interface, there's the GIMPshop developed by Scott Moschella.
Google has also developed Picasa which is a basic photo editing and organizing software which can be useful to photographers who only need to crop, fix red eye, and adjust the hues on their photos.