Tracking, like kerning, is a horizontal space adjustment of letters, but whereas kerning refers to the space relationship between two individual characters, tracking applies to the uniform spacing of groups of letters—whether it be a word, sentence, paragraph, or larger block of text. Tracking can range from very tight to very loose. Large headlines are often improved by some tightening of the tracking, and very small type can be made more legible by some loosening, especially if the paper it is to be printed on is absorbent and allows ink spread.