In addition to photographs, illustrations can be very useful to support a text. Often, people think of illustrations as drawings in children's books. However, that is not quite the same. The images in your communication are not composed of pixels (as photographs are). Instead, vectors are used. These are mathematical calculations, allowing the illustrations to be scaled without loss of quality.
Good examples ofillustrations aregraphs, diagrams, maps, offprint on company cars or façade windows, and technical drawings, but can also be used for background patterns. Icons for websites and apps are also illustrations and are often created as vector files.