A set of points on a straight line are called 'collinear points'.
An infinite set of points can be a microscopically small line segment. An infinite number of points does not mean an infinitely long line.
A set of three points not on the same line are points that define a unique plane.more than three points not on a plane are in a space (volume).
Collinear set of points
Collinear
line
These are collinear points.
colinear points
Two points.
A set of points forming a straight line.
It is a set if infinitely many points.
A line segment is a set of points between the two main end points. A line segment is always connected and has no open spaces.