# Converting and standardizing units of geometry and distance

Imagine that you have two points on the Earth's surface, with a straight line drawn between them:

Each of these points can be described as a coordinate using some arbitrary coordinate system (for example, using latitude and longitude values), while the length of the straight line could be described as the "distance" between the two points.

### Note

Of course, because the Earth's surface is not flat, we aren't really dealing with straight lines at all. Rather, we are calculating geodetic or **Great Circle** distances across the surface of the Earth.

Given any two coordinates, it is possible to calculate ...