This document defines key concepts related to obligations and contracts. It outlines the four elements of an obligation including the active subject, passive subject, object/prestation, and juridical tie. It then discusses a creditor's rights if the debtor fails to comply or acts in contravention of the obligation. The document also covers fortuitous events, the concept of delay, and the four successive rights of a creditor to satisfy a claim against a debtor. It defines what a contract is and its three essential elements. It provides various classifications of contracts and the three stages of a contract. Key aspects related to consent, fraud, defective contracts, voidable contracts, unenforceable contracts, and void/inexistent contracts are also