Although most commonly used to depict geography, maps may represent any space, real or imagined, without regard to context or scale; e.g. brain mapping, DNA mapping, and extraterrestrial mapping.
Road maps are perhaps the most widely used maps today, and form a subset of navigational maps, which also include aeronautical and nautical charts, railroad network maps, and hiking and bicycling maps.
The orientation of a map is the relationship between the directions on the map and the corresponding compass directions in reality. In the Middle Ages many maps, including the T and O maps, were drawn with East at the top (meaning that the direction "up" on the map corresponds to East on the compass). Several kinds of maps are often traditionally not oriented with North at the top:
Maps from non-Western traditions are oriented a variety of ways. Old maps of Edo show the Japanese imperial palace as the "top", but also at the centre, of the map. Route and channel maps have traditionally been oriented to the road or waterway they describe.
Typical maps of the Arctic have 0° meridian towards the bottom of the page; maps of the Antarctic have the 0° meridian towards the top of the page.
Reversed maps, also known as Upside-Down maps or South-Up maps, reverse the "North is up" convention and have South at the top.
- Buckminster Fuller's Dymaxion maps are based on a projection of the Earth's sphere onto an icosahedron. Modern digital GIS maps such as ArcMap typically project north at the top of the map, but use math degrees (0 is east, degrees increase counter-clockwise), rather than compass degrees (0 is north, degrees increase clockwise) for orientation of transects.
The same applies to computer maps where the smallest unit is the pixel. Some maps, called cartograms, have the scale deliberately distorted to reflect information other than land area or distance. Near the center of the map stations are spaced out more than near the edges of map.
Maps of the world or large areas are often either 'political' or 'physical'. Topographic maps show elevations and relief with contour lines or shading. Perhaps the best-known world-map projection is the Mercator projection, originally designed as a form of nautical chart.The functionality of maps has been greatly advanced by technology simplifying the superimposition of spatially located variables onto existing geographical maps.
replacing the map by a more detailed one