Above the fold is the part of an email that is visible in an email client without having to scroll. Content in this area is considered more valuable because the subscriber sees it first.
The term was originally used to describe the top-half of the front page of a folded newspaper. Unlike a newspaper, email fold locations are not predictable. Your fold may be affected by your subscribers' preview pane, monitor-size, monitor resolution, and headers placed by email programs such as Gmail.
