This document discusses properties and theorems related to angle congruence. It defines angle congruence as a relation that is reflexive, symmetric, and transitive. It also presents several theorems: all right angles are congruent; angles that are supplementary or complementary to the same (or congruent) angles are congruent; angles forming a linear pair are supplementary; and vertical angles are congruent. Examples are provided to illustrate using these properties and theorems to prove statements about angles.