The Marvel Cinematic Universe is more than just action-packed fighting, cool super suits and memorable one-liners. Over the last decade, Marvel has been dropping hints — Easter eggs, along with mid-credit and post-credit scenes — to set up one of the biggest showdowns in Marvel comic book history: “Infinity War.” It’s hard to remember every semi-hidden tip over 10 years, but we’ve got you covered.

What are the Infinity Stones?

The Infinity Stones, or as they’re known in the comics, Infinity Gems, are a group of six stones that allow “its owner complete omnipotence over one aspect of the universe,” according to Marvel. The six gems are: Space, Time, Reality, Mind, Power and Soul; they’re scattered, protected or hidden throughout space. Having all the rare stones make their owner the most powerful being in the universe, allowing him or her to shape it as they see fit. In the case of Marvel Studios’ big baddie, Thanos, it gives the Mad Titan the ability to bring balance to the galaxy by wiping out half of it with a simple snap of his fingers.

Iron Man 2008

Iron Man (Robert Downey Jr.) returns to his Malibu mansion at night to be greeted by Nick Fury (Samuel L. Jackson), director of S.H.I.E.L.D. Fury asks Stark, "You think you're the only superhero in the world?" and says he is there to discuss the "Avenger initiative." One can consider this end-credit scene to be the "big bang" of the Marvel Cinematic Universe because it is this scene that created a billion-dollar franchise. This moment between Fury and Stark propels the Marvel Cinematic Universe storyline forward as Stark gathers superpowered members to form "The Avengers."

Iron Man 2 (2010)

Many will be shocked to see “Iron Man 2” on the timeline, but you probably blinked and missed a huge MCU Easter egg. The Tesseract, an important plot point in “Captain America: The First Avenger” and “The Avengers” makes a brief appearance as Tony watches old film reels left behind by his father, Howard Stark. In one of Starks' notebooks, there is a drawing of the hypercube, which is a container for the Space Stone (one of the six Infinity Stones).

Thor (2011)

In a post-credit scene, Dr. Erik Selvig (Stellan Skarsgård) meets Nick Fury at a secret facility where Fury shows him the Tesseract. Fury tells Selvig that if they figure out how to tap into it, it could lead to unlimited power. Loki (Tom Hiddleston), appears in a mirror and says, "I guess that's worth a look," which Selvig repeats, foreshadowing Loki's role as the villain in “The Avengers.”

Captain America; The first Avenger (2011)

Captain America (Chris Evans) and the villain of this film, Red Skull (Hugo Weaving), are fighting aboard a plane carrying HYDRA's weapons of mass destruction. During the fight, the container that holds the Tesseract is damaged. Red Skull grabs the Tesseract, a portal into another universe opens, and he disappears through it. Red Skull has yet to reappear in any Marvel film.

The Avengers (2012)

After transporting Red Skull to another universe, the Tesseract is recoered by S.H.I.E.L.D. Loki steals it and uses it to open a portal that brings the Chitauri army to New York in “The Avengers.” At the end of the film, Thor (Chris Hemsworth) returns it to Asgard for safekeeping.

“The Avengers” is the first of Marvel's films to have mid-credits and post-credits scenes. During the mid-credits scene, The Other is seen talking to someone on a throne about why the Chitauri army failed to conquer Earth. The someone perched on the throne turns around grinning an evil smile. This is a pivotal point in the MCU, as it is the first time we see Thanos, one of the most powerful villains in the Marvel Universe, up close and personal.

Thor: The Dark World (2013)

The Aether, also known as the Reality Stone, is a main plot point in “Thor: The Dark World.” To give a little Asgardian history, there was an ancient war between the gods of Asgard and a race called the Dark Elves. Asgard won, and the Dark Elves' ultimate weapon, the Aether, was buried in a secret location that Dr. Jane Foster (Natalie Portman) accidentally stumbles upon. She becomes possessed by the Aether, and Thor takes Jane to Asgard to protect her before a Dark Elf named Malekeith (Christopher Eccleston) captures her to turn her into a weapon to destroy the entire universe.

In a mid-credits scene, after helping Thor defeat Malekeith, Volstagg (Ray Stevenson) and Sif (Jaimie Alexander) take the Aether to the Collector (Benicio del Toro). They entrust the Aether to him because the Tesseract is still in Asgard and it would be unwise to have two Infinity Stones in close proximity. After they leave, the Collector says, "One down, five to go," revealing his intentions to also collect the Infinity Stones. The Collector will also reappear in “Guardians of the Galaxy,” thus pushing the Infinity War storyline forward.

Captain America; Winter soldier 2014

This after-credit scene sets up “Avengers: Age of Ultron” as we are introduced to the villain the Avengers will fight: Baron von Strucker (Thomas Kretschmann). As he walks a dark corridor with Loki's scepter in hand, he says, "What they have “is worth more than any of them ever knew,” and they have “only scratched the surface.” The Twins — Scarlet Witch (Elizabeth Olsen) and Quicksilver (Aaron Taylor-Johnson) — are then revealed. They are seen locked away, using powers granted to them by the Mind Stone/Loki's scepter.

Guardians of the Galaxy 2014

As with other MCU films, another plot is centered around another Infinity Stone, specifically the Power Stone. Peter Quill (Chris Pratt) obtains the Orb from an ancient ruin, and to no one's surprise, the Collector and Ronan the Accuser (Lee Pace) want the Orb. Ronan (Thanos' adopted son) agrees to retrieve the Orb for Thanos until he discovers that it contains an Infinity Stone that would allow him to destroy the planet Xandar without Thanos' help. Ronan attempts to destroy Xandar with the Power Stone but is stopped by the Guardians.

After Ronan acquires the Power Stone, Nebula (Karen Gillan) aligns herself with him. Theories suggest that she will be the key to destroying Thanos in “Infinity War.”

After Gamora (Zoe Saldana) is arrested on Xandar, Thanos summons Ronan and Nebula (Thanos' adopted daughter) to Chitauri Space. Ronan tells Thanos that Gamora has betrayed them, which is why they are not in possession of the Orb. Ronan asks Thanos to take the matter seriously and Thanos declares that he could not care less about him or politics. He orders Ronan to bring him the Orb and threatens to kill him if he fails.

Remember The Collector? Gamora (Thanos' adopted daughter) and the Guardians meet up with the Collector, where it is revealed that the Orb contains an Infinity Stone, the Power Stone. He also describes the origin of the stones — “Before creation itself, there were six singularities. Then the universe exploded into existence, and the remnants of these systems were forged into concentrated ingots. Infinity Stones. These stones, it seems, can only be brandished by beings of extraordinary strength.”

Avengers; Age of Ultron 2015

Tony Stark (Robert Downey Jr.) and Bruce Banner (Mark Ruffalo) used Loki's scepter (i.e. the Mind Stone) to create an evil, highly intelligent robot named Ultron (James Spader). Ultron realizes that the Mind Stone is inside the scepter and forces Helen Cho (Claudia Kim) to create a new body for him. The Avengers stole the body before Ultron could insert his consciousness into it. Stark and Banner repurposed the stolen body with components of Stark's personal AI J.A.R.V.I.S., giving birth to Vision (Paul Bettany), who currently has the Mind Stone embedded in his forehead.

In this post-credit scene, we see Thanos putting on the Infinity Gauntlet. This is key because the Infinity Gauntlet's purpose is to hold all six Infinity Stones, granting the wearer the ability to use the power of each stone in combination. When all six Infinity Stones are placed in the gauntlet, the wearer can essentially do whatever they want.

The Avengers raid a HYDRA facility commanded by Baron Von Strucker, whom we caught a glimpse of in the post-credit scene from “Winter Soldier.” While infiltrating the facility, Wanda uses her powers against Thor, causing him to hallucinate. In this vision, he sees Heimdall (Idris Elba) with whited-out eyes yelling that they are all dead and that he is a destroyer. However, what he is actually seeing is Ragnarok, which in Norse mythology is their version of the apocalypse. This first vision sets up for “Thor: Ragnarok.” During this first vision, he catches a glimpse of Vision and the other Infinity Stones. Thor departs to ask Dr. Selvig for help and they go to a mystical pool which allows for Thor to delve deeper into the vision. During this second vision, he sees all four of the Infinity Stones revealed thus far (Power, Space, Reality and Mind).

Captain America: Civil War 2016

Even though there are not any Infinity Stones hidden in plain sight, “Civil War” gives insight into the emotional state of the super-powered team. The events in “Age of Ultron” and the Sokovia Accords drive a wedge between teammates. The disagreement between Iron Man and Captain America comes to a climax in an action-packed battle where we are introduced to two new characters pivotal for “Infinity War” — Black Panther (Chadwick Boseman) and Spider-Man (Tom Holland).

Doctor Strange 2016

MCU introduces another Infinity Stone hidden in plain sight called the Time Stone. Doctor Strange (Benedict Cumberbatch) acquires an amulet called the Eye of Agamotto and in the film, uses it to control time to defeat the demon Dormammu.

Thor: Ragnarok 2016

During a post-credit scene, Thor, the Revengers, refugees from Sakaar and people of Asgard are on a ship looking for a new home. Loki and Thor look out into space filled with a hope that is quickly crushed when they encounter a large, menacing ship. The ship resembles the large Chitauri spaceships seen in “Avengers,” which means that the ship belongs to Thanos (Josh Brolin). This post-credit scene sets up for a likely encounter in “Infinity War” between Thanos and Thor's crew on the ship.

And Now…

That brings us to Marvel Studios’ “Avengers: Infinity War,” one of its biggest and most ambitious undertakings. The film is, in many ways, the culmination of what Marvel has been working toward over the last 10 years, and includes nearly all of Marvel’s mightiest heroes. But “Infinity War” has many questions it’ll need to answer, such as where is the final Soul Stone, will Thanos succeed in his mission to wipe out half of the universe, and who will be left alive when the war for the Infinity Stones comes to an end?