Function f: x ? y – Meaning and Explanation

Question

I am doing IGCSE Maths, and am having a few problems with function notation. I understand the form $f(x)$.

What does the form $f: x ↦ y$ mean? Could you also give one or two examples?

And, if possible, state your source. Thank you.

Answer 1

It means that $f$ is a function that takes the value $x$ to the value $y$. For instance, $$f: x\mapsto x^2$$ is an alternate way of writing $f(x) = x^2$.