After 10 years and 18 movies, the Marvel Cinematic Universe has become the most financially successful franchise in film history.
But that also means there has been a lot to keep track of before "Avengers: Infinity War," one of the most ambitious crossover events, comes to cinemas later this month.
The movie is already projected to be a major success.
But even if "Avengers: Infinity War" breaks box-office records, not everyone who watches it will have seen all the other MCU movies or remember all the details. That doesn't mean it can't still be enjoyable — but since this is the movie the others have been leading up to, it's best to know the basics.
For those who need a crash course or a refresher on the MCU, we've compiled all the important details and events you'll need to know before heading to the theater when "Infinity War" is released April 27.
In the first "Avengers," way back in 2012, Thanos (Josh Brolin) provides the army that Loki (Tom Hiddleston) leads in the attack on New York City.
Obviously, the Avengers put a stop to that attack, so we can assume Thanos isn't happy with Loki.
Based on trailers for "Infinity War," it's almost guaranteed that Loki hands over the Space Stone — one of six Infinity Stones that Thanos is after that give him reality-bending powers — to Thanos, who may very well use it to end Loki's life. Maybe. (He doesn't show up in any other scenes in the footage we've seen.)
During the post-credits scene in "Thor: The Dark World," the Collector (Benicio del Toro), who collects rare artefacts across the galaxy, is given the red Reality Stone. As far as we know, it's still in his possession for "Infinity War."
Star-Lord (Chris Pratt) was able to hold the purple Power Stone in "Guardians of the Galaxy" — with the help of the other Guardians — because, as it was revealed in "Guardians of the Galaxy Vol. 2," his father is a powerful cosmic entity.
His father is also evil and wanted to spread himself across the entire universe, but that's another story.
Because Star-Lord is only half human, though, he was able to wield the Power Stone without getting obliterated, as anyone else would be. That could prove useful when the Guardians and the Avengers take on Thanos in "Infinity War."
After the Guardians discover the stone's destructive power, they put it in the hands of the Nova Corps, a galactic police force. But in trailers for "Infinity War," Thanos has the purple stone, meaning he must take it from the Corps at some point before or during the movie.
After faking his death and going into hiding in "Captain America: The Winter Soldier," Nick Fury (Samuel L. Jackson) showed up again "Avengers: Age of Ultron" to help the Avengers defeat Ultron. But he hasn't been seen since, and we're not sure whether he'll show up in "Infinity War." He does, however, play a prominent role in next year's "Captain Marvel," which is set in the 1990s and stars Brie Larson as the title character.
Hawkeye (Jeremy Renner) does indeed have a family, which was a subplot of "Age of Ultron" because he's a character who writers have no idea what to do with.
He went into retirement because of it, but he briefly came out to join Captain America's (Chris Evans) side in "Captain America: Civil War." But Hawkeye hasn't been featured in any promotional material for "Infinity War," raising the question of what exactly he's doing — and whether he'll survive.
The directors Joe and Anthony Russo recently said that they "did not forget the twice-nominated Jeremy Renner" and that his story was a "long play."
Vision's (Paul Bettany) origin has been messy since he first appeared in "Age of Ultron," which is a messy movie. But he's basically an android created by Ultron — another android created by Tony Stark/Iron Man (Robert Downey Jr.) — to be his perfect body.
But the Avengers got to the body first, and it gained sentience by combining with Stark's artificial intelligence, Jarvis, and the yellow Mind Stone, which is in Vision's forehead. All you really need to know is that Vision is an android with one of the stones Thanos is after. In "Infinity War," the Avengers bring Vision to T'Challa/Black Panther's (Chadwick Boseman) home of Wakanda to protect him and take a stand against Thanos.
Vision and Scarlet Witch (Elizabeth Olsen) also have somewhat of a romantic connection — which previous movies haven't really elaborated on — that will be a focal point of "Infinity War."
"Age of Ultron" explored a romantic relationship between Bruce Banner/The Hulk (Mark Ruffalo) and Black Widow (Scarlett Johansson), but it was just a convenient plot point: Widow would calm the Hulk down when he got out of control. Again, that movie is kind of a mess, but we assume this will at least be acknowledged in "Infinity War."
In "Captain America: Civil War" — after the battle with Ultron leaves the nation of Sokovia in ruins in "Age of Ultron" and Scarlet Witch accidentally kills innocent people early in the film — the government proposes superhuman registration, which would essentially make the Avengers government employees.
Captain America says that would strip away their freedom, while Iron Man thinks it could be beneficial by putting their powers in check. By the end of the film, Captain America and his team of Avengers who took his side are fugitives who didn't register. He breaks his friends out of a high-tech prison at the end of the movie, and that's where "Infinity War" picks up with many of the characters.
But the threat of Thanos brings them together, and they'll have to put aside their differences if they want to save the universe.
During the battle between Captain America's and Iron Man's sides in "Civil War," War Machine (Don Cheadle) is shot down by Vision, and the resulting crash cripples him. But by "Infinity War," thanks to some Stark tech, he's not only walking again, but flying the War Machine armor too.
At the end of "Captain America: Civil War," just as it seems as though Iron Man/Tony Stark is coming around to Captain America's side, he learns that Bucky Barnes (Cap's best friend) killed his parents years earlier while brainwashed by the terrorist organisation Hydra. So coming into "Infinity War," Bucky and Iron Man aren't exactly getting along. Captain America sends Iron Man a nice letter at the end of "Civil War" letting him know he's there if Stark he needs him, but there's sure to still be tension among the two, since Cap is in Bucky's corner.
Doctor Strange (Benedict Cumberbatch) wears the green Time Stone around his neck in the Eye of Agamotto, which contains and controls it. I wouldn't say this means death for Strange though. Because he's one of the more recent characters to appear in the MCU, Marvel Studios will probably keep him around.
Gamora (Zoe Saldana) and Nebula (Karen Gillan) are Thanos' adopted daughters — something that looks as though it will be explored in "Infinity War" in flashbacks, as evidenced by this shot. They want him dead, but at the end of "Guardians of the Galaxy Vol. 2," Nebula vows to go after him alone. The lone-wolf mentality might not be the best option against someone as powerful as Thanos.
You may have noticed Spider-Man/Peter Parker (Tom Holland) has a new suit in the "Infinity War" trailers — it's the one Stark presents him at the end of "Spider-Man: Homecoming" when Parker is offered a spot on the Avengers.
He initially turned it down, but it looks as if the threat of Thanos brings Spider-Man together with the Avengers, and he takes advantage of the high-tech suit as well.
It's reminiscent of the "Iron-Spider," the suit Spider-Man dons in the comics during Marvel's "Civil War" event.
Thor (Chris Hemsworth) believed he got his power from his hammer, Mjolnir, but it was revealed in "Thor: Ragnarok" that it was focusing his power — he is, after all, the God of Thunder.
So now that Mjolnir is destroyed — crushed by his evil sister, Hela (Cate Blanchett) — Thor knows he can wield his powers without it.
He also lost an eye during his battle with Hela, but Hela was seemingly killed during the apocalyptic event Ragnarok, which destroys Thor's home of Asgard, at the end of the movie.
After Asgard is destroyed, Thor and his fellow Asgardians set off in a ship to find a new home.
During a mid-credits scene in "Thor: Ragnarok," a much larger ship stops them. We can assume this is Thanos — as well as that the scene where Loki hands over the Space Stone takes place right after this.
It's obvious that something bad happens to the Asgardians, as the Guardians end up finding Thor in space.
At the end of "Black Panther," T'Challa chooses to reveal Wakanda to the world. Up until that point, the African nation had been in isolation, refusing to share its wealth and technology with other nations. Maybe he'll come to regret that, as much of the action in "Infinity War" takes place in Wakanda.
After the events of "Civil War," T'Challa took in Bucky and gave him safety in Wakanda. After the credits of "Black Panther," we see him being taken care of by T'Challa's sister, Shuri (Letitia Wright).
We know where all the other stones are, but the location of the orange Soul Stone has yet to be revealed. Is it in Wakanda? Is it hiding in plain sight?