Mathematicians write Q.E.D. at the bottom of a proof. It is short for the Latin phrase which means "which was to be shown". It indicates that the conclusion of the proof is the statement that we set out to prove.
How can we be sure that software meets requirements? We set out to provide some business value, and we end up with code. How do we know that the conclusion of that code is the satisfaction of business requirements?
Q.E.D. coding practices produce software that is mathematically provable. We can code with confidence.
