**(i) Line segment:** The part of a line that connects two points or we can say that a shortest distance between the two points. A line segment is one-dimensional.

Here AB is a line segment.

**(ii) Collinear points:** Two or more points are said to be collinear if all the points lie on same line.

**(iii) Parallel lines :** Two lines in a plane are said to be parallel lines if they do not intersect each other.

Here l and m are parallel lines.

**(iv) Intersecting lines: **Two lines are intersecting if they have a common point. The common point is known as point of intersection.

Here l and M are intersecting lines. And P is point of intersection.

**(v) Concurrent lines:** Two or more lines are said to be concurrent if there is a point which lies on all of them.

Here l, m and n are concurrent lines.

**(vi) Ray:** A straight line extending from a point indefinitely in one direction only.

Here OA is a ray.

**(vii) Half-line:** If A, B. C be the points on a line l, such that A lies between B and C, and we delete the point A from line l, the two parts of l that remain are each called a half-line.