Lines in geometry are straight and extend in either direction forever. The only way to stop a line point from extending is by using an endpoint. An endpoint is just a small dot that appears at the end of the line to indicate where it stops. To indicate the name of the line, place dots on either side of the line with a letter. When the line doesn't stop, it should have an arrow attached to the end of the line to indicate that it goes on forever in a single direction. Lines are referred to by their two points, such as "line AB."
A point is labeled with a letter or number to indicate a position on a plane. Points do not have a specific size, they only identify an exact location. Regardless of the size of the actual point, it does not define an actual size. Instead, it merely defines a location on a line, or a place on a plane. The individual letters or numbers used make it possible to define the exact point referred to.
A ray acts very similarly to a line in geometry. With a line, both ends move in opposite directions indefinitely. With a ray, only one side of the line extends forever. The other side is indicated by an endpoint. Similar to a line, rays are labeled by indicating the starting point and the point the ray passes through. For example, a ray with points A and B refers to "ray AB."
Lines interact with each other in geometry in one of two ways. Since lines move forever in both directions, at some point if they aren't exactly parallel they will intersect with each other. Lines that are parallel will follow each other but never intersect. When two lines do intersect, the point at which they meet is called a common point and labeled with a letter. When lines are parallel they are written as "line AB || line CD" to indicate they are parallel.