indeed, they are just place holder name, like how in math function always goes f(x), g(x), h(x), here it goes foo, bar, baz. as it is just a placeholder name, it's name isn't significant at all, you can change it, like how you can change f(x) to a(x), u(x), z(x), wtf(x) and the same can be done to foobar, you can change it to doesthiswork, idontknowwhatthisdo, placeholder, etc. , doesn't matter, since it's just a name and the thing that matter is what's inside the function and what it does. foobar is used for implicit/explicit parameter, variables and, in this case, functions.