Important days happen inside the world of movies, just like they happen beyond the silver screen. No spoiler alert required: Characters pin their hopes, fears, and special occasions on particular dates and years.
Look to Oct. 3, which has significance to "Mean Girls" fans, as that's when a cute boy asks our heroine the day. "Blade Runner" mavens hold 2019 dear to their dystopian hearts, "Empire Records" fans know April 8 is Rex Manning Day, and as for Oct. 21, 2015?
Well, call it the Internet's most revisited, incorrectly shared, and obsessed-over movie date. That's the day that Marty McFly and Doc Brown traveled to the future in the second installment of "Back to the Future," the date seen on the digital read-out inside Doc's souped-up DeLorean.
It's a digital read-out that's been meme'd and remixed a bunch in recent years, with various proclamations stating, regardless of the actual date on the calendar, that "this is the day Marty McFly went to the future!"
Consider Oct. 21, 2015 the one true and correct date. Done. Finito. Final.
And consider the ways you can celebrate the auspicious -- or at least highly dramatic -- date with other "Back to the Future" fans: ArcLight Hollywood is screening all three films in the Dome on Wednesday, Oct. 21, and a full-on fan gathering called We're Going Back shall set its DeLorean gently down in the City of Angels from Oct. 21 through Oct. 25 in honor of the film's 30th anniversary.
Visits to the Universal Studios Hollywood backlot -- also known as Hill Valley's town square -- and other flux capicator-powered happenings shall dominate the multi-day super fan happening.
No spoilers about what happens to Marty and Doc in the future -- and, as of this typing, Oct. 21, 2015 is still the future, for all of us -- but let's just say that things went kerplooey all around, thanks to Biff's shenanigans, a statistics-laden sports almanac, and Marty encountering his grown-up self.
Just know, the next time you get a photo of the DeLorean digital display with the assertion that today, whenever "today" might be, is the day that Marty McFly travels to the future, that Oct. 21, 2015 is the only right date.
And in the "Back to the Future" universe, being correct about the date, and even the exact minute -- clock tower lightening strike, anyone? -- is essential to its fan-pleasing, intricately looped plot lines.
Please, though, Doc Brown: Do be careful where you discard that sports almanac on Oct. 21. The future -- er, the past -- depends on it.