Once simply a campy sci-fi series of the 1970s and 80s, "Star Wars" has grown into an omnipresent pop culture behemoth with its own theme park and a never-ending stream of movies, television series and merchandise.

But if you still can't quite get enough of the galaxy far, far away, the iconic franchise has its own holiday, too – even if it's one entirely made up.

Saturday is "Star Wars" Day, the unofficial celebration of the beloved space opera that falls every year on May 4. That means plenty of "Star Wars" festivals in cities across the nation, special deals from retailers looking to capitalize on the hype and – fingers crossed! – perhaps an announcement or two from Disney about the future of the franchise.

Here's everything to know about "Star Wars" Day.

'Star Wars' Day:Celebrate May the 4th with these deals

Why is May 4 'Star Wars' Day?

It's no accident that "Star Wars" Day is celebrated on May 4.

Anyone who is a fan of the series knows well that Obi-Wan Kenobi and other Jedi often use the phrase, "May the force be with you," as a sentiment of good will. Well, as fans have come to realize, the phrase can sound a lot like "May the 4th be with you" – and a holiday was born.

So, yes, the date on which "Star Wars" Day is celebrated every year is based solely off of a pun.

When did 'Star Wars' Day start?

Because it originated as a fan holiday, "Star Wars" Day has no official origin or even commencement year.

The earliest uses of the phrase “May the 4th Be With You” dates to 1978, one year after the release of "Star Wars: Episode IV – A New Hope," according to StarWars.com. It didn't take long for the vernacular of the film to become ingrained in American popular culture, as “May the force be with you,” had been appearing on buttons, posters and other items for months after the film's release.

By that summer, newspaper writers used the phrase as a gimmick to mark Independence Day celebrations on July 4, according to StarWars.com.

Another one of the earliest uses of the phrase came on May 4, 1979, when a London newspaper writer congratulated Britain’s new prime minister, Margaret Thatcher, on her first day of office, StarWars.com says. In a full-page ad the writer said, “May the Fourth Be With You, Maggie. Congratulations!”

The phrase resurfaced once again in July 2005, weeks after the release of "Star Wars: Episode III – Revenge of the Sith." A marketing push to bring audiences back to theaters inspired a newspaper ad with Yoda in front of a patriotic background of red-white-and-blue fireworks with the phrase, “May the Fourth Be With You,” at the top.

But the concept didn't really start taking off until the advent of social media as users began using it in hashtags. Though it began as a way for fans to host themed parties or revisit the films, retailers were quick to take advantage of the trend with marketing pushes of their own.

Where to watch 'Star Wars' shows, movies

Because May 4 falls on a weekend this year, it may be the perfect time to kick back and host a "Star Wars" marathon.

All 11 of the live action films – the three trilogies and two standalones, "Rogue One" (2016) and "Solo" (2018) – are available to stream on Disney+.

Starting May 4, "Star Wars" fans will also be able to watch all nine films that comprise the "Skywalker Saga" in select theaters nationwide to celebrate the 25th anniversary of "Star Wars: Episode I – The Phantom Menace."

Disney, which acquired Lucasfilm in 2012, has tirelessly churned out plenty of "Star Wars" content in the ensuing years, including both live-action and animated series that are also available on its streaming platform.

Just in time for "Star Wars" Day, the latest series, the "Tales of the Empire," will hit Disney+ on Saturday. The animated series created by Dave Filoni follows two characters in different time periods as they fight the evil Galactic Empire.

Check out the trailer here:

Monthly subscription rates for Disney+ start at $9.99.

Eric Lagatta covers breaking and trending news for USA TODAY. Reach him at [email protected]