Today’s a huge day for nostalgia. It’s “Back to the Future” Day, or, the day in the future, in “Back to the Future II,” Marty visits to save his family.

Plenty of corporations are on board. Pepsi is launching Pepsi Perfect – used in the movie – to commemorate the day, but its limited rollout has people upset. Lexus is trying to get in on the fun with some hoverboard concept. People are tweeting about “Jaws 19” – and some people are even reviewing it – and on and on.

I’m a huge fan of the “Back to the Future” trilogy. The first is my favorite movie ever. It’s been that way since probably high school. I suspect some early millennials feel the same way.

It’s funny millennials have such a strong reaction to the “Back to the Future” trilogy, but it makes sense. Despite the original coming out when the oldest millennials were 3, and despite the 1989 sequel appearing when the oldest millennials were 7, the movies have garnered greater interest on VHS and on cable. Moreover, they’re perfect movies for the internet age: images from the movies are meme-ready, quotes from the movies are Twitter-ready, and concepts from the film (hoverboard, Cafe ’80s, etc.) are easily re-imagined today.

Plus, there’s the nostalgia factor. The original “Back to the Future” offered nostalgia for the carefree 1950s. This came at the very end of an era of ’50s nostalgia (“Grease,” “Happy Days,” “American Graffiti”), and was meant to appeal more to Generation Xers and their Silent Generation parents. But because the sequel offers nostalgia for the ’80s, it immediately allows kids from the ’80s to take part, too. Thus millennials get hooked onto the films quicker.

Because the film then offers a possible 2015 reality, it pulls in everyone, including the young people not even born in 1989. It’s actually a genius way to keep a movie timeless while keeping it completely dated in 1985 (even the sequel feels like it’s made in 1985).

In essence, the “Back to the Future” trilogy is nostalgia for anyone born between 1925 and 2000, spanning four generations.

That’s heavy.