Movies have soundtracks, the background music or score that accompanies the visual action. Sometimes it is referred to as the theme music.

When it is done well, we tend to remember the soundtrack from a movie for a long, long time.
For instance, from the classic "The Wizard of Oz" (1939), I'd say many of us would remember the song "Somewhere over the Rainbow".
I also bet you can whistle the theme music from the war movie "The Bridge over River Kwai" (1957) or the western "The Good, the Bad and the Ugly" (1966).

And what about that tearjerker "Love Story" (1970) ? Then there's the theme music of "The Godfather" (1972), "Star Wars" (1977) and "Forrest Gump" (1994) which are so memorable.
Your children would probably know the theme music from the Harry Potter movies.
Someone once asked me: what is the soundtrack of your life? Like the soundtrack of a movie, the music might go high or low, faster or slower, louder or softer based on the significant events of your life. Think about it for a moment. What is the soundtrack of your life?