There are four points on a straight line. There is only one straight line with four points, and each point has two rays and eight rays. Any two of these four points can have a line segment. * * * There are: 3+2+ 1=6 line segments.

Ray refers to a straight line formed by the infinite extension of one end of a line segment. Light has only one endpoint, and its length cannot be measured (infinite length).

A line segment means that both ends have endpoints and cannot be extended, which is different from straight lines and rays.

Extended data:

The difference between a ray segment and a straight line:

(1) Endpoint: A straight line has no endpoint; Ray has only one endpoint; A line segment has two endpoints.

(2) Extension: Both sides of a straight line can extend indefinitely; The other end of the ray endpoint can be extended indefinitely; The line segment cannot be extended.

(3) Measurement: Lines and rays cannot be measured, but line segments can be measured.

(4) It means: straight line: a line without end points; Ray: a line with only one end; Line segment: A line with endpoints at both ends.