A representation of the surface of the earth, or of some portion of it, showing the relative position of the parts represented; -- usually on a flat surface. Also, such a representation of the celestial sphere, or of some part of it., Anything which represents graphically a succession of events, states, or acts; as, an historical map., To represent by a map; -- often with out; as, to survey and map, or map out, a county. Hence, figuratively: To represent or indicate systematically and clearly; to sketch; to plan; as, to map, or map out, a journey; to map out business.
A map's legend shows what symbols and their meaning is used on the map.
The map key is a list of symbols and their meaning used in the map.
map
Key
'Chart', as in, a sea map.
map keys
A conformal map preserves shape, meaning angles are maintained. A equal-area map preserves size, meaning areas are accurately represented.
map
The meaning of symbols on a map are stated in the legend for that map which will be attached to it or printed in one corner of the map.
A map's legend help people to understand the meaning of words and symbols used in the map.
This is usually known as the "key", or "legend".
A key explains the symbols on the map and tell you what they represent, such as YHA meaning a Youth Hostel, PH meaning a Public House or a + representing a chapel.