Naming of rays Rays are commonly named in two ways: By two points. In the figure at the top of the page, the ray would be called AB because starts at point A and passes through B on it's way to infinity. Recall that points are usually labelled with single upper-case (capital) letters. There is a symbol for this which looks like this: AB This is read as "ray AB". The arrow over the two letters indicates it is a ray, and the arrow direction indicates that A is the point where the ray starts. By a single letter. (I have not seen this done.) The ray above would be called simply "q". By convention, this is usually a single lower case (small) letter. This is normally used when the ray does not pass through another labeled point.