How many endpoints does a ray have?
A ray has many points, but it has only one endpoint. The rest of
the points extend away from the endpoint infinitely along a linear
path.
This is different than a line segment, which has two endpoints
between which a finite distance can be measured. A ray's length is
infinite, but only in 1 direction away from its endpoint.
A sunbeam can be thought of as a ray. The sun is like the
endpoint. Each beam of light begins at the sun and radiates away
from it in one direction. Some of the sun's rays point in a path
toward Earth. Other rays point in different directions, either
passing by us, or going in a direction away from us.