**One common example of perpendicular lines in real life is the point where two city roads intersect.** When one road crosses another, the two streets join at right angles to each other and form a cross-type pattern. Perpendicular lines form 90-degree angles, or right angles, to each other on a two-dimensional plane.

Other real-world examples of perpendicular lines include graph paper, plaid patterns on fabric, square lines of floor tiles, lines of mortar on brick walls, the intersecting lines of a Christian cross, metal rods on the cooking surface of a barbecue grill, wooden beams in the wall of a house, and the designs on country flags such as Norway, the United Kingdom, Switzerland, Greece, Denmark and Finland. Perpendicular lines form the corner of squares and rectangles in various real-world shapes.

Perpendicular lines create four right angles at their intersection point, making 360 degrees total. Perpendicular lines also form one angle of a right triangle. Perpendicular lines are concepts taught in algebra and geometry as students learn to calculate slopes of lines on graph paper.

Parallel lines differ from perpendicular lines in that parallel lines never intersect. Real-world examples of parallel lines include railroad tracks, stripes on the American flag, power lines hung between poles, lines on composition paper and plugs at the end of electrical cords.