ImageMagick and GD are software libraries that need to be present on a server in order for images to appear on a particular internet site. They allow you to perform different tasks with the images - create, flip, resize, change colors, etcetera. These things can certainly be performed 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 site or for the image to be resized automatically with regards to the device and resolution the site visitor is using. Both ImageMagick and GD can be used with many web programming languages like PHP, Perl and Python, so you don't need to stick to only one language to create your website. They work with more than a hundred formats, which includes the most widely used ones - JPEG, GIF, TIFF, PNG, and so on.