There are numerous alternate dimensions or universes in this shared multiverse. While normally separate from one another, there would be ways to open portals
Earth-1610 is the home universe of two versions of Spider-Man: a Peter Parker who died at 26, and Miles Morales. It was the Wilson Fisk of this universe that inadvertently opened a portal between six dimensions (theirs and five others).
In the comics, Earth-616 is the "prime-universe" — the main setting of most of its non-alternate universe storylines.
- Earth-8311 on the Marvel wiki