Board Thread:News and Announcements/@comment-5047768-20131003005753/@comment-4651179-20131003204110

We know what Earth is each comic from because we are also told so. When Marvel publishes a comic that takes place in another Earth, you not only notice differences in the comic's context and characters to the regular universe, but also because Marvel sometimes uses different types of imprints to publish different universes. As an example, every title from Earth-90214 (the Noir Universe) has the word "Noir" in its title, most of the titles that take place in Earth-1610 (the Ultimate Universe) have the word "Ultimate" in their titles.

And as I previously mentioned, one of the easiest ways to realize when two characters are from the same Earth is when they crossover. You know the Iron Man movies take place in the same Earth as the Captain America movies because they've interacted (e.g.: The Avengers movie) and have numerous connections.

It's easy to recognize when what you are reading takes place in another Earth.

And we also know which Earth is which because we are also told which Earth is which. Here's a list of every single reality from the Marvel Multiverse.