This website sums it up well (and then goes into detail if you are interested):
“A function is a way of matching the members of a set “A” to a set “B”:
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Citation: Pierce, Rod. (19 Apr 2020). “Injective, Surjective and Bijective”. Math Is Fun. Retrieved 17 Oct 2020 from http://www.mathsisfun.com/sets/injective-surjective-bijective.html
Additional notes (from “Bijection,” Wikipedia, retrieved 10/17/20):
- An injective function is also sometimes called “one to one” (because each B has at most one A and each A has exactly one B).
- A surjective function is sometimes called “onto” (because every B has at least one A).
- A bijective function is sometimes called a “bijection,” a “one-to-one correspondence,” or an “invertible function.”
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Disclaimer:
I am not a professional in this field, nor do I claim to know all of the jargon that is typically used in this field. I am not summarizing my sources; I simply read from a variety of websites until I feel like I understand enough about a topic to move on to what I actually wanted to learn. If I am inaccurate in what I say or you know a better, simpler way to explain a concept, I would be happy to hear from you :).
