A lead-in is a short phrase, usually five words or less, that starts off a photo caption in a newspaper, high school yearbook, magazine or other publication.
Lead-ins (a.k.a. "kickers") are used to catch the reader's attention and "lead in" to the main caption. These phrases widely range from common phrases to song lyrics, and are written appropriate to the subject matter of the photograph. This is separate to lead in which makes reference to getting new business into a sales team, typically.
Examples of lead-ins include the following: