BalanceOf<T> as explained by Kian

snip.rs

struct Foo;
struct Kian;
struct Shawn;

trait Bar {
	type Buzz;
}

impl Bar for Foo {
	type Buzz = u32;
}
impl Bar for Kian {
	type Buzz = u16;
}
impl Bar for Shawn {
	type Buzz = u8;
}

type BuzzFoo = <Foo as Bar>::Buzz;
type BuzzKian = <Kian as Bar>::Buzz;
type BuzzShawn = <Shawn as Bar>::Buzz;

type BuzzOf<T> = <T as Bar>::Buzz;
// BuzzOf<Foo>
// BuzzOf<Kian>
// BuzzOf<Shawn>

// <Type as Trait>::AssociatedType;

// BalanceOf<Runtimes> // u128 / type Balance = u128
// BalanceOf<T>;
type BalanceOf<T> =
	<
		// The given T implements the config trait of my pallet.
		<T as Config>::Currency
		as
		// The "currency associated type" of my config, implements traits::Currency.
		frame_support::traits::Currency<<T as frame_system::Config>::AccountId>
	// which MUST HAVE an associated type called Balance, regardless.
	>::Balance;

// BalanceOf<T::Currency>
type BalanceOf<C> = <C as Currency<_>>::Balance;