Map is relation between two sets A and B, characterized in that, that to each element a from A, one and only one element b of B is related.
Aerial view by Googlemap at 35.48636, 139.2162
Wikipedia suggests, that
map is a symbolic depiction emphasizing relationships between elements of some space, such as objects, regions, or themes. (2020) 
In many cases, map is simplified representation of some object with its projection to two-dimensional space.
Representation of Earth with a bidimentional picture is also called map. Such a map can be complicated, especially if the creator tries to represent the relief of the surface. 
In century 21, there are several sites that provide on-line maps:
- https://en.wikipedia.org/wiki/Map A map is a symbolic depiction emphasizing relationships between elements of some space, such as objects, regions, or themes. (2020)