Image Editor

An image editor is a program that allows you to open and edit images (also known as photographs and pictures).

Image editors come with all sorts of capabilities and are intended for many types of uses:

A simple image viewer with some basic editing built-in - such as IrfanView and Picasa - these products are freeware.
A little more advanced product like Picture Manager or Photo Editor that comes bundled as part of Microsoft Office.
Image editors meant for amateur digital photographers - these include Microsoft Digital Image Pro, Corel Photo Album, Adobe Photoshop Elements, Ulead PhotoImpact, etc.
More advanced programs that include full multiple layer support and tons of editing options - these include Adobe Photoshop and Corel Paint Shop Pro.