Lined paper, also known as ruled paper, is paper printed with evenly-spaced horizontal lines in order for people to keep their handwriting linear and organized. The lines are usually blue and thin. Lined paper also often comes with two vertical lines on either side of the page, usually pink, to provide margins and tab stops.

Medium ruled (or college ruled) paper has 9⁄32 in (7.1 mm) spacing between horizontal lines, with a vertical margin drawn about 1 1⁄4 inches (32 mm) from the left-hand edge of the page. Its use is very common in the United States.