Blip

"You remember everyone Thanos snapped away five years ago and just bringing them back to now, today... Don't change anything from the last five years."

- Iron Man to Hulk

The Blip was the occurrence in which Bruce Banner wore Tony Stark's Nano Gauntlet. As Hulk snapped his fingers, the effects of Thanos' Snap on the universe were reversed, with the deceased half of its population being resurrected five years after their demise.

Background
"All right, the glove's ready. Question is: who's gonna snap their frickin' fingers?"

- Rocket Raccoon As all of the Infinity Stones are gathered back into the present, the Avengers realized Black Widow sacrificed herself to gain the Soul Stone. Determined to not let Natasha’s sacrifice be in vain Tony Stark, Rocket Raccoon, and Bruce Banner began working on a new Infinity Gauntlet. After the creation of the Gauntlet was complete, Rocket asked who was going to be the one to reverse the Snap.

Blip
"You saw what those stones did to Thanos, they almost killed him. None of you could survive." "How do we know you will?" "You don't. But the radiation's mostly gamma. It's like I was made for this."

- Hulk and Captain America At the moment when the Nano Gauntlet was set for completion, Thor volunteered himself to put it on, but the Avengers held him back, saying he was neither physically nor emotionally stable enough to do so. Thor, however, was stubbornly adamant about wearing the gauntlet, as lightning flowed in him. However, Bruce Banner knew from the calculations that Thor would most likely die from the attempt at wearing, much less snapping his fingers. So Banner volunteered himself, reasoning that as the Stones and his body contained mostly gamma radiation, he was the most likely to survive the use of the Gauntlet. While Stark ordered F.R.I.D.A.Y. to initiate lockdown procedures across the facility in case the Gauntlet's energies proved to be too powerful to contain, an alternate Nebula began to sabotage the quantum device as Banner put on the Gauntlet. The Avengers began worrying for him as Banner channeled the power of the Stones through his body, severely scorching his arm up to his shoulder in the process. With his last sign of power, Banner snapped his fingers, which ultimately brought everyone who Thanos snapped back to life in either the area they disappeared at five years ago or a nearby safe alternative.

As the team finally won the battle, the Sanctuary II emerged and crashed through the roof of the facility, destroying the quantum device.

Attack on the New Avengers Facility
"I will shred this universe down to its last atom and then, with the stones you've collected for me, create a new one teeming with life that knows not what it has lost, but only what it has been given. A grateful universe." "Born out of blood." "They'll never know it. Because you won't be alive to tell them."

- Thanos and Captain America

Ant-Man guessed that the mission of resurrecting the universal population worked, as he looked at the inner garden at a flock of birds that appeared out of nowhere, while at the same time Hawkeye received a call from his wife, who had previously perished in the Snap. As the group started to realize their mission had been completed, a dazed Bruce Banner looked up and noticed Thanos' mothership from above the window ceiling. Before he could react, the Sanctuary II fired upon New Avengers Facility, destroying it and causing the Avengers to be separated from each other in the collapsing debris, although Hawkeye is able to take possession from the Gauntlet during his fall into the sewers. Rogers, Stark, and Thor were the only members to have remained on the ground level floor. The trio then confronted the time-remnant Thanos of 2014, who now sought the Stones to reset the universe in his image. This confrontation happened concurrent to the time-remnant 2014 Nebula who tricked an exhausted Barton into handing her the Nano Gauntlet. Following a long struggle, Stark and Thor were soon rendered out of commission, leaving Rogers left to face Thanos, who summoned the full of his armada. The effects of the Blip then became apparent during the ensuing battle when Captain America received a transmission from Falcon, one of the victims of the Snap, and the rest of those resurrected started appearing shortly thereafter through portals created by Doctor Strange and other sorcerers. Ant-Man then became Giant-Man upon finding Banner, Rhodes, and Rocket buried under the facility ruins, carrying them to the surface for the final battle with Thanos. With the united army of Allied Avengers, Rogers lead the charge against Thanos' forces.

Behind the Scenes

 * The term "Blip" originated in Spider-Man: Far From Home, used to describe both half of the population disappearing due to Thanos' Snap as well as their resurrection five years later. However, following the movie's release, Kevin Feige clarified that despite Marvel Studios internally referring to both events as the Blip, the MCU fans adoption of the term "Snap" would now be used to denote Thanos' use of the six Infinity Stones, while "Blip" would henceforth be referred to as Bruce Banner's reversal of the Snap.