Point: A point has no length, breadth and thickness i.e., it has no magnitude. It has position only. It is regarded as an entity of zero dimensions. A point is always named with capital letters.
Line: A line has only length and no breadth or thickness. It is regarded as an entity of one dimension.
Straight line: A straight line is the shortest distance between two given points.
Curve line: A curved line is nowhere straight. There are endless varieties of curved lines.
Horizontal line: A horizontal line is perfectly level.
Oblique line: An oblique line is neither horizontal nor vertical.
Parallel lines: Parallel lines are lines in the same direction. They cannot meet however far they may be produced.
Ray: A ray is a portion of a line that begins at some point. A ray has one end point.
Line segment: A line segment is a portion of a line. A line segment has two end points.