If you press the tip of a pen or pencil on a piece of paper, you get a fine dot, which is called a point. A point is used to show the location and is represented by capital letters - A, B, C.
A line is extended infinitely on both sides and is marked with arrows. A line is named using any two points on it like AB or by a single small letter l, m.
The part of the line between two points A and B is called a line segment and is named AB.
One and only one line can be drawn passing through two given points.
If you mark a point X and draw a line, starting from it extending infinitely in one direction only, then you get a ray XY. X is called the initial point of the ray XY.
f a line can pass through three or more points, then these points are said to be collinear. If a line can not be drawn passing through all three points (or more points), then they are said to be non-collinear.
Since two points always lie on a line, we talk of collinear points only when their number is three or more.