How do I use ImageMagick?

ImageMagick is an image manipulation software suite for a wide variety of formats, released under a General Public License compatible free license. A number of websites use ImageMagick's features, such as Wikipedia, whose MediaWiki software uses ImageMagick to process and present images. An X Window GUI front end for ImageMagick exists, in addition to a command line version. The program uses magic numbers to identify the image file formats, and is also why "Magick" appears in the name.