ImageMagick and GD are software libraries which should be present on a server for images to appear on a certain site. They enable you to perform various tasks with the images - create, flip, resize, change colors, etcetera. These things can easily be done online and in real time, so if you add a static image, for instance, the libraries make it possible for a thumbnail to show up on the website or for the image to be resized automatically depending on the device and resolution that the visitor is using. Both ImageMagick and GD can be used with various web programming languages such as PHP, Perl and Python, so you do not need to stick to a single language to develop your website. They work with more than a hundred formats, including the most popular ones - JPEG, GIF, TIFF, PNG, and so on.