Maps are visual representations of territories. Like pictures, they can exist either on paper or similar material support or in people’s minds, as so-called mental maps. Cartosemiotics, the semiotics of maps, has therefore interdisciplinary connections with both cartography and cognitive science. Situated between the semiotics of pictures, mental representation, and the semiotics of codes, cartosemiotics belongs to the general field of Applied Semiotics: since maps usually contain written language and are signs encoded by certain cartographic conventions, they also need to be decoded. This combination of graphic and verbal elements makes them complex semiotic systems.
Like pictures, maps represent surfaces and space through a two-dimensional medium. Since maps are two-dimensional media, they can represent space much better than words, which have to be pronounced in a linear sequence. At the same time, maps make use of an elaborate system of symbols to locate or describe geographical loci. Cartographic representations are usually provided with a legend to facilitate the interpretation of its signs.