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).
The most common cartographic convention is that north is at the top of a map.
It is important to recognize that even the most accurate maps sacrifice a certain amount of accuracy in scale to deliver a greater visual usefulness to its user.
For example, the width of roads and small streams are exaggerated when they are too narrow to be shown on the map at true scale; that is, on a printed map they would be narrower than could be perceived by the naked eye.
Mapping larger regions, where curvature cannot be ignored, requires projections to map from the curved surface of the Earth to the plane.
The impossibility of flattening the sphere to the plane without distortion means that the map cannot have constant scale.
Maps not oriented with north at the top: Many maps are drawn to a scale expressed as a ratio, such as ,000, which means that 1 unit of measurement on the map corresponds to 10,000 of that same unit on the ground.
The space being mapped may be two dimensional, such as the surface of the earth, three dimensional, such as the interior of the earth, or even more abstract spaces of any dimension, such as arise in modeling phenomena having many independent variables.
The orientation of a map is the relationship between the directions on the map and the corresponding compass directions in reality.
The word "orient" is derived from Latin oriens, meaning east.
Another example of distorted scale is the famous London Underground map.
The basic geographical structure is respected but the tube lines (and the River Thames) are smoothed to clarify the relationships between stations.