lead-in

/L EH1 D IH0 N/
noun
  1. 1

    An introduction; something that leads into the beginning of something.

    โ€œAfter the long lead-in, the climax of the story was a disappointment.โ€

  2. 2

    A region of data at the beginning of a compact disc, holding the table of contents.

  3. 3

    A short phrase that begins the caption of a photograph.

Source: https://en.wiktionary.org/wiki/lead-in