Product placement is a form of advertising in movies and television shows, in which the advertiser of a product pays a fee (or offers another consideration) in return for having the products seen on screen. In the Back to the Future trilogy, the amount of product placement ran the full spectrum from subtle background uses to becoming a major part of the plot.
Uses of product placement
On the DVD commentary to the three films of the trilogy, Robert Zemeckis and Bob Gale commented on the different uses of product placement in the film. The first was that in which an agent for the studio would make a bargain with an advertiser to feature products in return for a fee, without any control by the director. Zemeckis noted that Universal Studios had recently created a product placement department that would contract with different advertisers to put an item in the film. Bob Gale commented later that "The lesson I learned on this and the subsequent sequels is I never do product placement, ever, anymore... I never take money anymore. It's like you've got another creative person." Zemeckis added, "You have another producer." .
The product placement department had made a deal with the California Raisin Board, accepting $50,000 to place a reference to raisins in the film. Since raisins do not photograph well, the placement was on a bench upon which Red the Bum was seen sleeping when Marty returned from 1955. "When the California Raisin Board saw it," recounted Gale, "they were livid," and the money was refunded. 
Another form of placement, under the control of the producers, relied upon specific brands and logos to make the film more realistic. Zemeckis commented that "In terms of creating the image of the past, one of the ways you create the past is through brand names. We made a conscious effort to find products that had a different logo in the past. It used to be, in [movies of] the 60s or the 70s, a car would pull into a gas station, and there would be no name on the gas station. That's ridiculous. Somebody owns that gas station." 
For the first film, businesses whose logos had been different in 1955 than in 1985 were sought out. Although bids were made for Shell Oil and Coca-Cola to be seen in the film, the producers chose Texaco and Pepsi respectively, because their logos had been noticeably different in 1955. Zemeckis comments that "A Coke bottle in the 50s and a Coke bottle in the 80s were the same,"  Likewise, in painting a picture of what 2015 might be like, the producers sought futuristic products in return for placement. For the third film, which took place in 1885, references to brand names were fewer, although not entirely non-existent.
Both the Miller Brewing Company and Budweiser were visible in Hill Valley, with trucks from both companies on the streets in 1985, and cans of both Lite Beer and Bud Lite present in the McFly family refrigerator. After wrecking George McFly's car while drinking beer, Biff Tannen took a light beer from the refrigerator and complained about it. In 1955, only Miller Beer was present in Hill Valley; Marty passed a delivery truck on his way into downtown, and Sam Baines had an open bottle of the beer at his dinner table. Lorraine Baines McFly drank Popov vodka.
The McFly family kitchen included such products as Scott Towels, Raid insecticide, Pledge wash, Kellogg's Cocoa Krispies (and two other Kellogg's cereals, the names of which are almost completely obscured on-screen), Maxwell House coffee, Wonder Bread, McCormick pepper, French's Instant Potatoes and French's mustard, and Scott bathroom tissue. George McFly purchased Sophie Mae peanut brittle. The family played board games, and "The Game of Life", made by Milton Bradley, sat near the television.
Doc fed Einstein both Kal Kan canned dog food and Milk Bone dog biscuits. In 1955, he had fed Copernicus Milk Bone dog biscuits as well. At Lou's Cafe, Mounds and Almond Joy candy bars were sold at the cash register.
It should perhaps also be mentioned that in George Gipe's Back to the Future novelization, George McFly is eating Rice Krispies at Lou's Cafe, but this cannot count as an example of product placement as the cereal is never referred to by name on-screen, and no cereal box is visible.
In the sequel, brand names were especially prominent, particularly in updated versions created for the world of 2015. Hill Valley was awash with products from such brands as Pepsi, Nike, Mattel, Pizza Hut, Black & Decker, The Weather Channel, Texaco, 7-Eleven, AT&T, and others.
Several Nintendo games would appear in the movie. Most notable example is Marty demonstrating his playing skills on the arcade port of Wild Gunman. Jaws (produced by LJN) and BurgerTime appear briefly shown in the window of Blast from the Past.
Pizza Hut provided not only their company name, but a professional food stylist and pizza kitchen to be at the set of the future McFly house to make hot, attractive pizzas for each take.
On the other hand, there was almost no product placement in 1885, the setting for the final part of the trilogy, although a member of Buford's gang commented on the word "Nee-kay" (Nike) on Marty's "moccasins". Also, the name of the Wells Fargo building was prominent as Marty dodged a stagecoach which is now the bank's logo, and a Tabasco sauce bottle is seen when Chester picks up the ingredients for the wake-up juice.
Marty also mentioned learning how to shoot at 7-Eleven (where he had played the video game Wild Gunman), and picked up a pie plate from the Frisbie Pie Company, concluding that he could use it as a frisbee.
Pepsi did make an appearance in the third film, although not to the extent that it was seen in Parts I and II. A billboard advertisement for Pepsi can be seen, however, at the Pohatchee Drive-In Theatre in 1955.
In "Super Doc", when Marty was sitting in the audience, he was behind a sign that said Fepsi, rather than Pepsi.
- JCPenney (in the opening of "Back to the Future: The Game - Episode 1: It's About Time" and on the title menu) was changed to JPPinney.
- Similarly, Robinson's department store was changed to Rubarison's.
- Tab (Soda shown at the beginning of "Back to the Future: The Game - Episode 4: Double Visions") was changed to Alt.
- Mattel (Mattel hoverboard used at the end of "Back to the Future: The Game - Episode 5: OUTATIME") was changed to Attell.