Contour maps depict spatially-varying values, such as elevation, by means of curves of equal value.
A contour represents all points where the value of a function is a constant. Collections of contour lines, or contour maps, are often used to depict spatially-varying functions, typically elevation.
Questions tagged with "contour" typically pertain to the construction, interpretation, or processing of contour maps.
Synonyms include "contour line", "isoline," ["isarithm,"](http://en.wikipedia.org /wiki/Contour_line) "level set," "isocontour," and "implicit curve." In specific applications, where the function in question has a conventional meaning (such as pressure, temperature, etc.) contours are often called "iso-X" where "-X" is related to a Greek or Latin name for the same quantity; e.g., "isobar" ("equal pressure") and "isotherm" ("equal temperature").