(i) Line-segment- Give two points A and B on a line l, the connected part (segment) of the line with end points at A and B is called the line segment AB.
(ii) Collinear points – Three or more points are said to be collinear if there is a line which contains all of them.
(iii) Parallel lines – Two lines l and m in a plane are said to be parallel lines if they do not intersect each other.
(iv) Intersecting lines – Two lines are intersecting if they have a common point. The common point is called point of intersection.
(v) Concurrent lines – Three or more lines are said to be concurrent if there is a point which **** on all of them.
(vi) Ray – A line in which one end point is fixed and the other part can be extended endlessly.
(vii) Half-line – If A, B, C be the points on a line l, such that A **** between B and C, and we delete the point A from line l, the two parts of l that remain are each called half-line.
