It's been about 10 years in the making, but now it's finally here.

"Avengers: Endgame" represents the culmination of almost two dozen feature films about superheroes in the Marvel Cinematic Universe. The new release opens Thursday, April 25.

But getting an admission ticket to see one of the most highly anticipated movie sequels of the year-adapted from comic books or otherwise-may require superhuman effort.

Earlier this month, advance ticket sales for the movie clogged websites like AMC's, with traffic volume about 10 times higher than normal. And for Fandango, the film exceeded the first day U.S. sales record set by "Star Wars: The Force Awakens" within the first six hours of presales.

What began with a B-list superhero Iron Man and Robert Downey Jr., a troubled actor who wasn't a bankable A-lister, became one of the most popular (and profitable) franchises in showbiz.

In fact, chances are you've watched at least one or more of the over 20 movies (and more than 10 television series) with colorful characters co-created by the late comic book icon Stan Lee.

But what if you haven't? And what if you don't have the time, or don't want to spend close to the 60 hours it would take, to watch at home the 22 movies leading up to "Avengers: Endgame"?

Beginning Tuesday, April 23, select theaters will be showing every single movie in the franchise, starting with "Iron Man" and working up to the three-hour "Avengers: Endgame," rated PG-13.

But just who (or what) are the Avengers? As a comic con veteran who, like many children, idolized spandex-wearing or masked heroes growing up, the Avengers are like an all-star team.

Spider-Man, Hulk, Thor and other superheroes have had their own adventures and sequels on the silver screen since 2008, but an Avengers movie is a pop culture battle royale.

Just like a slightly dysfunctional family around a Thanksgiving dinner table with one-too-many invites and not enough turkey legs to go around, the Avengers are a team of (powerful) misfits.

And like siblings vacationing at Disney, which owns Marvel Studios, members of Avengers, like Iron Man, will play nice with others if they have to, like Captain America, to fight a greater foe.

The enjoyment in previous Avengers movies comes from watching its members bicker with, take jibes at, make fun of or play pranks on one another while saving the planet and humanity.

The big baddie in "Avengers: Endgame" is Thanos, an extraterrestrial supervillain who has collected all the Infinity Stones, which gives him the power to kill half of the living universe.

His motivations are definitely questionable-a warped sense of wanting to establish equilibrium in a chaotic and sprawling universe-but his means are undoubtedly deadly and random.

At the end of "Avengers: Infinity War," Thanos snaps his fingers and half of the population disintegrates into dust. "Avengers: Endgame" seeks to reverse that apocalyptic ending.

Exactly how the remaining superheroes-many of whom became fan favorites through their solo cinematic adventures-accomplish that remains to be seen, but we can't wait to find out.