Every Marvel fan remembers that traumatic moment in Avengers: Infinity War when Thanos finally gathered all of the Infinity Stones and, with a simple snap of his fingers, wiped out half of the universe's population. That climactic moment needed a name, which ended up being (appropriately, albeit simplistically) referred to as the Snap.
Then came Spider-Man: Far From Home, which referred to the deadly moment as the Blip, leaving fans confused. In order to head off any confusion, Marvel Studios president Kevin Feige stepped in to clarify the distinct different between a Snap and a Blip in the Marvel Cinematic Universe. In an interview with Fandango, Feige explained:
"It came pretty fast. We always referred to it as the Blip, and then the public started referring to it as the Snap. We think it's funny when high school kids just call this horrific, universe-changing event the Blip. We've narrowed it down to—the Snap is when everybody disappeared at the end of Infinity War. The Blip is when everybody returned at the end of Endgame … and that is how we have narrowed in on the definitions."
Spider-Man: Far From Home is the first MCU movie to come after Endgame, so it has the hefty task of showing what the world is like after the Blip, as people return after five years. The people who survived aged normally, but those in the Blip didn’t age at all. It’s a whole exciting world of complexity, but at least we know how to speak about it properly.