Sometimes, knowing the history of a word helps you to understand what that word really means.

You call it line spacing, the space between lines of text. Designers call it "leading," based on its origin in the actual strips of lead metal that were used to create spaces between lines of type on old printing presses. In the world of typography, an "open" paragraph is one with wide spaces between lines. Conversely, a paragraph "set solid" has lines that are very close together. Leading is measured in points just like type. If you are working with 10 point type and you insert 2 point leading, those 2 points are added to the type size to become the leading size. We refer to that line of type as "10 over 12." Our computers automatically calculate leading for us (auto leading) using a standard of 20% of the type size to determine leading. But remember, you can over-ride this feature if you want to create a certain look or feel to deliver your message.