https://maximummathematics.com/books/foundational-mathematics/set-theory/size-of-a-set/index.htmlIn the previous section, we saw sets that can have vastly different numbers of elements. Some sets have a finite number of elements, meaning that if we started to list out all of that set’s elements, we’d eventually be able to stop, having written down every element. In contrast, some sets have infinitely many elements, meaning that if we start listing elements and stop at any point in time, there would still be elements missing.Hugoen-US