What are the pictures that represent something on a map called?

The pictures that represent something on a map are called symbols. Without symbols, it would be hard to represent several features typically found on a map, reduce the cost of production, and improve the appearance of a map.

Here are a few examples of things that you can find on a map which are represented by different symbols: Boundaries such as national, state, county and small parks, buildings such as school, airports, picnic area, cemetery, campground and winter recreation areas, coastal features such as coral reed, wreckage and sea wall, mines and caves such as mine shaft, tailings and mine dump, railroads such as railroad underpass and overpass, railroad yard and railroad tunnel, rivers, lakes and canals such as falls, steam and dam and roads such as highways and trails.