There are four types of lines: horizontal line, vertical line, perpendicular, and parallel lines. They are defined based on their orientation, and the angles if any, formed between them. Let’s look at each one of them.

## Horizontal line

A line that runs from left to right in a straight line is called a horizontal line.

## Vertical line

A line that runs from top to bottom in a straight line is a vertical line.

## Perpendicular

When two straight lines intersect (i.e.cross) each other at right angles (= 90°), then these two lines are said to be perpendicular to each other.

Here AB and CD are the two perpendicular lines, and they are represented as .

## Parallel lines

When two lines never meet each other, no matter how much you extend them, then these two lines are said to be parallel to each other.

Lines AB and CD are parallel lines, and are always the same distance apart from each other. Parallel lines are represented by the two large arrows on the lines, and are represented as