Unary operations only have one input while binary operations have two inputs. For example ++i is a unary operation since this statement only has one input value, i. On the other hand i + n is a binary operation (Not to be confused with the binary numeral system) since there are two inputs, i and n. i + n + z is still binary since it is actually 2 binary operations; i + n = x, then x + z = y or (i + n) + z.