The term CPCTC can come up a lot when you're dealing with congruent triangles, but what does it mean? This tutorial gives a great explanation and shows you how to use it in an example!
corresponding parts of congruent triangles are congruent
Understand that a two-dimensional figure is congruent to another if the second can be obtained from the first by a sequence of rotations, reflections, and translations; given two congruent figures, describe a sequence that exhibits the congruence between them.
When you have two congruent figures, that means that corresponding sides and corresponding angles are congruent. Get some practice identifying corresponding sides and angles by following along with this tutorial!