Bas relief is an artistic technique that involves lightly carving a design into a surface. Most coins have images stamped on them in bas relief.
In general, relief makes an artwork look like the picture is raised up from a flat background. There are two types of relief, high and low — or bas — relief. Bas relief is distinguished by the relative shallowness of the image, and you can see it in a lot of ancient Egyptian art. The French bas-relief is borrowed from the Italian basso-rilievo, "low relief" or "raised work."