Your website can be made faster by compressing scripts, stylesheets and other files, and by implementing caching. However, by far the easiest and most immediately enhancing technique to speed your website up is image optimization for the web.
The simple logic of web images
Images on the web are different. They don't need to be near as high quality, or the size as those produced by any modern digital camera. Cameras create large photos of printable quality. On the web all we are looking for is enough quality to look great on a screen, so we don't need near as much information in the file as we would for printing.