# Ray Line

A ray line is a portion of a line. It can be defined as a line segment which is extended indefinitely in one direction. It is bounded by a point on one side and is not bounded the other side. This point is called the end point (sometimes referred as beginning point too). The other side which has no bounds extends to infinity in one direction.

A ray is always a part of a line having one endpoint and a set of all points on only one side of the endpoint. In general, a ray is named by using two letters. The first letter must be the beginning point (endpoint) and the second letter being any point on the ray. An arrow with an endpoint over the letters is indicated to represent a ray. The above ray can be represented as $\overrightarrow{AB}$ where A is the endpoint and B is any point on the ray.

A light from a flash light is a real life example for a ray. The origin of the light which is the torch becomes the end point and one cannot measure exactly the distance the light travels in the direction pointed to. Sun rays are the best examples for rays starting from the end point Sun and goes in different directions and infinite distances.