ELI5: Explain Like I'm 5

Actual infinity

Actual infinity is the idea that some things can go on forever and never end. We can think of numbers this way. Numbers can go on forever, starting with 1, then 2, then 3, and so on. No matter how many numbers we think of, we can always think of one more! We can never reach the last number because it never ends! People argue about if actual infinity exists or not.
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