This document discusses the definition and classification of contracts. It defines a contract as a legally enforceable agreement between two or more parties. There are several requirements for a valid contract such as agreement, consideration, capacity, legality, and form. Contracts can be bilateral, requiring promises from all parties, or unilateral, requiring an act from one party. They can also be express, written out, or implied, based on conduct. The document outlines different types of contracts and discusses how they are interpreted, focusing on interpreting the plain meaning and considering the contract as a whole.