Coordinate System 

A special class of coordinate systems are those where each line of one set intersect at right angles to every line of the other set. Such a system is called an Orthogonal Coordinate System.
Here are some orthogonal coordinate systems in two dimensions
Cartesian Coordinate System  Coordinate curves are both straight lines  named after the inventor of the system René Descartes  
Polar Coordinate System  Coordinate curves are circles and straight lines  
Parabolic Coordinate System  Coordinate curves are both parabolas  
Bipolar Coordinate System  Coordinate curves are both circles  
Elliptic Coordinate System  Coordinate curves are ellipses and hyperbolae 
By extension Coordinate Systems exist for three and more dimensions.