Product placement is when a movie shows a product, or set of products, in return for a fee or payment in kind from that product’s manufacturer. It happens all the time, as Morgan Spurlock’s new documentary, “The Greatest Movie Ever Sold,’’ makes plain. Spurlock blows the whistle on product placement the way his “Super Size Me’’ did on fast food in 2004.

Product placement belongs to the realm of commerce and advertising. Really, what’s product placement but a commercial by other means? Related to product placement, but quite different from it, is something you might call product emplacement, which belongs to the realm of entertainment and imagination. That’s when a particular product is so integral to a movie that it becomes part of film lore. No money changes hands. What changes is movie history.

James Bond illustrates the difference. One of the more notorious examples of product placement was BMW’s three-picture deal with Bond producers to have its Z3 roadster used as 007’s car, starting with “GoldenEye.’’ Part of what made that switch such a big deal was that Bond had been indelibly associated with a quite different vehicle, the Aston Martin DB5. He first drove it in “Goldfinger.’’ Bond, famously, has a license to kill. So long as he’s behind the wheel of that Aston Martin we know he has a license to drive, too.

Motor vehicles have a special place in product emplacement. Sometimes they’re two-wheeled. Riding a Vespa in “Roman Holiday’’ helped make Audrey Hepburn a star. Marlon Brando was already a star when he climbed atop a Triumph Thunderbird, in “The Wild One.’’ But it was the image of him straddling that motorcycle that made him an icon.

Usually, the vehicle has four wheels. Steve McQueen roared around San Francisco in a Mustang GT in “Bullitt.’’ The DeLorean in the “Back to the Future’’ movies roared through time. The Clint Eastwood character’s lovingly preserved 1972 Ford gives “Gran Torino’’ its title. A certain Disney -owned VW Beetle stars in not one, but five theatrical releases: “The Love Bug,’’ “Herbie Rides Again,’’ “Herbie Goes to Monte Carlo,’’ “Herbie Goes Bananas,’’ and “Herbie: Fully Loaded.’’

The most notorious instance of product emplacement is one of the all-time great marketing fiascos. Mars found the title character of “E.T.’’ so ugly it refused to let Steven Spielberg use M&Ms as a lure for the creature. Instead, Reese’s Pieces were used — and sales of the product went up 65 percent once the film was released.

No products are more central than the toys in the “Toy Story’’ series. After all, it’s their story, right? The main toy characters originated with the filmmakers: Woody, Buzz Lightyear, Jessie. But others derive from preexisting toys: Mr. Potato Head, Slinky Dog, Etch-a-Sketch, Mr. Spell, Barrel of Monkeys, Barbie, and Ken.

Tom Hanks has a niche to himself in product-emplacement history. Besides being the voice of Woody, his being a FedEx employee and obsession with a Wilson volleyball figure prominently in “Cast Away,’’ and he drinks 15 Dr Peppers at a White House reception in “Forrest Gump.’’ That said, Billy Wilder’s “One, Two, Three,’’ not “Gump’’ is the “Citizen Kane’’ of soft-drink movies. James Cagney plays a Coca-Cola executive in West Berlin at the height of the Cold War — and the movie’s can’t-miss kicker comes courtesy of Pepsi .

Can product emplacement be aural as well as visual? If it can, then the “Saturday Night Fever’’ soundtrack has to be a contender for number one on the list. John Travolta, that movie’s star, had another brush with product-emplacement immortality, courtesy of his University of California at Santa Cruz Banana Slugs T-shirt in “Pulp Fiction.’’

Yes, colleges can benefit from product emplacement, too. Think of Harvard with “Love Story’’ — or “The Social Network.’’ The university received a record number of applications for undergraduate admissions this year. Think of it as a different form of friending.

Mark Feeney can be reached at mfeeney@globe.com.

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