Tracking is the amount of space between letters, words, or block of text. If you, have two people write out the same sentence by hand you will see that each may have a different amount of space between their letters and then even more space or less space in between their words.
Graphic designers look at this when they are laying out text for their publications. Generally, some sort of text manipulation has gone on if you see a piece done by a graphic designer. For example, to fit an paragraph into an area and not have one left over word hanging out the bottom, the designer may decrease the tracking of the whole paragraph to get rid of that hanging word. Designers may also increase tracking to add drama such as a heading that possibly uses the word long.
Tags: Define, paragraphs, spacing, tracking, typography, What is