A statement we accept without proof is called postulate. Postulate is also known as an axiom and they are considered to be the basic structure in which lemmas and theorems are taken from. One of the best example of a postulate is the five postulates popularly known as Euclid's postulates where Euclidean geometry is derived. It seems to be the source of the logical explanations and statements used in solving and explaining specific problems. Another example is the use of an SSS postulate to prove that a triangle is congruent thus, both sides are equal.
