The Law on Obligations and Contracts by Hector De Leon is one of the most important legal texts in Philippine law. It is a comprehensive guide to understanding the laws that govern contracts and obligations in the country and is used by lawyers, law students, and legal professionals in the Philippines.

The book is divided into two parts. Part one covers the law on obligations, while part two covers the law on contracts. Each part is further divided into chapters that cover specific topics related to the law on obligations and contracts.

Part one of the book covers the nature and kinds of obligations, their sources, extinguishment, and modes of performance. It also covers the various types of obligations such as civil obligations, natural obligations, and conditional obligations. Additionally, it delves into the different modes of extinguishing obligations such as payment, dation in payment, compensation, novation, and prescription.

Part two of the book covers the different types of contracts such as sale, lease, agency, loan, deposit, partnership, and agency. It delves into the essential elements of contracts, such as consent, object, and cause. It also covers the different types of defects that may affect the validity of a contract such as mistake, fraud, and violence.

Overall, the Law on Obligations and Contracts by Hector De Leon is an essential reference for anyone involved in Philippine law and legal practice. It provides a thorough understanding of the legal concepts and principles that govern obligations and contracts in the country. It is a valuable tool for lawyers, law students, and legal professionals who need to navigate the complex world of contracts and obligations in the Philippines.