In this section we collect many short essays designed to help you understand how to read, understand and construct proofs. Some are very factual, while others consist of advice. They appear in the order that they are first needed (or advisable) in the text, and are meant to be self-contained. So you should not think of reading through this section in one sitting as you begin this course. But be sure to head back here for a first reading whenever the text suggests it. Also think about returning to browse at various points during the course, and especially as you struggle with becoming an accomplished mathematician who is comfortable with the difficult process of designing new proofs. \techniqueappendix{D}{Definitions}{definition} \techniqueappendix{T}{Theorems}{theorem} \techniqueappendix{L}{Language}{mathematical language} \techniqueappendix{GS}{Getting Started}{starting proofs} \techniqueappendix{C}{Constructive Proofs}{constructive proofs} \techniqueappendix{E}{Equivalences}{equivalence statements} \techniqueappendix{N}{Negation}{negation of statements} \techniqueappendix{CP}{Contrapositives}{contrapositive} \techniqueappendix{CV}{Converses}{converse} \techniqueappendix{CD}{Contradiction}{contradiction} \techniqueappendix{U}{Uniqueness}{uniqueness} \techniqueappendix{ME}{Multiple Equivalences}{equivalences} \techniqueappendix{PI}{Proving Identities}{identities} \techniqueappendix{DC}{Decompositions}{decomposition} \techniqueappendix{I}{Induction}{induction} \techniqueappendix{P}{Practice}{practice} \techniqueappendix{LC}{Lemmas and Corollaries}{lemma}