Composer John Williams is responsible for some of the most recognizable music in film history: the epic fanfares in “Star Wars,” the two-note dread of “Jaws” and too many other examples to name without sounding like an IMDb tour of popular American cinema.

A new documentary, “Music by John Williams” (streaming on Disney+), introduces audiences to the man behind all of that music, featuring extensive interviews with Williams and glowing interviews with filmmakers he has worked with, including Steven Spielberg (also a producer of the movie), George Lucas and J.J. Abrams.

Laurent Bouzereau, the documentary’s director, first met Williams while directing making-of features for the home video releases of Spielberg movies, including “Jaws,” “Jurassic Park” and “Raiders of the Lost Ark.”

In a phone interview, he said the project started as part of Williams’ 90th birthday celebration, but it became clear it would be a waste to not do a full documentary combining his interviews with Spielberg’s archival footage of Williams, now 92, scoring his films. “I wanted people to understand his dedication to an art form,” Bouzereau said. “John is an eternal student.”

Here are some takeaways from the film.

When he first heard the “Jaws” theme, Spielberg thought Williams was joking.

Early in the documentary, Williams recounts the first time he played the opening music to “Jaws” for Spielberg.

The director thought he was joking. “I was expecting something just tremendously complex, and it’s almost like ‘Chopsticks,’ “ he says.

Williams kept telling him to listen to it again, until it clicked. “You feel like something dangerous is coming your way, just from these low notes in an atmosphere where they don’t belong,” Williams says.

That two-note score is in more of the movie than the film’s famously defective mechanical sharks, which the theme allowed to be in scenes without actually being onscreen.

“His musical shark worked a lot better than my mechanical shark,” Spielberg says in the documentary.

One of Williams’ sons is the lead singer of the ‘80s band Toto.

Williams played piano in studio orchestras for films like “To Kill a Mockingbird” and “The Apartment,” before leaving the orchestra performance jobs to focus on writing, in part to make more money for his three children.

In the documentary, Williams’ daughter, Jenny, talks about growing up in a musical household, recalling early memories of her father playing piano.

One of her brothers, Joseph, is the lead singer of the rock band Toto. (He joined after the band recorded its biggest hits, “Africa” and “Rosanna.”) Her other brother, Mark, is a drummer who has played with Crosby, Stills & Nash and Air Supply.

And Williams was married to singer and actress Barbara Ruick, who played Carrie Pipperidge in the 1956 film adaptation of the musical “Carousel.”

Williams had a career as a jazz musician.

When Lucas needed a composer for “Star Wars” who could do classical orchestrated scores, Spielberg told him he should work with Williams. Lucas, a jazz fan, recalls in the documentary that he responded, incredulously, “Isn’t he a jazz pianist?”

He was both. Williams recorded several jazz albums early in his career, including “Jazz Beginnings,” “The John Towner Touch” and “Rhythm in Motion,” where he was still credited as Johnny Williams.

He would lean on his jazz roots for the score to “Catch Me If You Can” in 2002, but one famous “Star Wars” song offers an earlier hint of Williams’ jazzy bona fides.

“It’s hard to imagine someone writing a piece like the cantina scene while knowing absolutely nothing about jazz,” saxophonist and composer Branford Marsalis says in the documentary. “I’ve heard really bad attempts at that kind of stuff, and it comes across as a cliched affectation at best.”

Williams is not a movie lover.

In the documentary, Williams admits that he’s not that much of a cinephile. “I was never a movie buff, or movie fan, then as now,” he says. He got his start in film music by taking a cue from his father, who played drums in studio orchestras, first for radio and then, after a move to Hollywood, for films, including Leonard Bernstein’s score for “On The Waterfront.”

Williams’ father took these scores home, sparking his son’s interest in composing film music himself. “I began to think that I could also do that,” he says in the documentary.