Identity Element
From Conservapedia
An identity element is that element of a set of numbers which, when combined with another number in a particular operation, leaves that number unchanged.
Zero (0) is the identity element under addition for the real numbers. If a is any real number, a + 0 = a and 0 + a = a.
One (1) is the identity element under multiplication since a × 1 = a and 1 × a = a.
