ImageMagick and GD are software libraries which should be present on a web server for images to appear on a particular site. They enable you to carry out different tasks with the images - create, flip, resize, change colors, etcetera. These things can be done online and in real time, so if you include a static image, for instance, the libraries make it possible for a thumbnail to appear on the site or for the image to be resized automatically with regards to the device and resolution that the visitor is using. Both ImageMagick and GD can be used with a lot of web programming languages like PHP, Perl and Python, so you don't have to stick to a single language to build your internet site. They work with more than one hundred formats, including the most widely used ones - JPEG, GIF, TIFF, PNG, and so forth.