Ray:
A ray is a term used in geometry to describe a straight line that starts at a single point and extends infinitely in one direction. It can be visualized as a line with an arrowhead on one end, indicating the direction in which it extends. Rays are often represented by drawing a solid dot at the starting point and an arrowhead at the other end.

Beam:
A beam, on the other hand, refers to a collection of rays that travel in the same direction and are parallel to each other. It consists of multiple rays that are emitted from a single point and spread out over a wide range. Beams are typically represented by drawing multiple parallel lines with arrowheads at one end.

Differences between a ray and a beam:
1. Direction:
- Ray: A ray has a specific direction in which it extends infinitely.
- Beam: A beam consists of multiple rays that travel in the same direction and are parallel to each other.

2. Starting point:
- Ray: A ray starts at a single point and extends infinitely in one direction.
- Beam: A beam is emitted from a single point and spreads out over a wide range.

3. Representation:
- Ray: A ray is represented by drawing a solid dot at the starting point and an arrowhead at the other end.
- Beam: A beam is represented by drawing multiple parallel lines with arrowheads at one end.

4. Extent:
- Ray: A ray extends infinitely in one direction.
- Beam: A beam spreads out over a wide range, but each individual ray within the beam may have a limited extent.

5. Parallelism:
- Ray: A ray is not parallel to any other line since it extends infinitely in one direction.
- Beam: A beam consists of multiple rays that are parallel to each other.

Conclusion:
In summary, a ray is a single straight line that extends infinitely in one direction, while a beam is a collection of parallel rays that travel in the same direction and spread out over a wide range. Rays have a specific starting point and direction, while beams are emitted from a single point and consist of multiple parallel rays.