CSS properties can control dimensions (height, width) as well as placement of images (float, align-right)
Images may be placed as the background to HTML elements (background-image) with properties controlling repetition, distortion, and scrolling with page
Search Engine Optimization: Use of semantic HTML (examples: image alt-text, links to/from other sites) to increase preference of a site in search engine results
Aided by analysis of where web traffic is coming in from