Epoxy resins are a class of versatile, thermosetting polymers that have gained significant attention due to their exceptional properties and diverse applications. This chapter explores the chemistry and types of epoxy resins, highlighting their synthesis, curing mechanisms, and structure–property relationships. The chapter begins by discussing the fundamental chemical principles underlying the formation of epoxy resins, including the ring-opening polymerization of epoxide monomers and the role of curing agents in the crosslinking process. Subsequently, the review categorizes epoxy resins based on their chemical composition, such as bisphenol A, bisphenol F, novolac, and aliphatic epoxy resins. Each type’s unique characteristics and advantages are examined, emphasizing their mechanical, thermal, and chemical resistance properties. Furthermore, the article delves into the various curing agents employed in epoxy resin systems, including amines, anhydrides, and catalytic curing agents, and their influence on the final properties of the cured material. The review also addresses the recent advancements in epoxy resin technology, such as developing bio-based and sustainable epoxy resins and incorporating nanofillers and reinforcements to enhance their performance. Finally, the article presents a comprehensive overview of the diverse applications of epoxy resins across industries, including coatings, adhesives, composites, electronics, and construction. This typical chapter serves as a valuable resource for researchers, engineers, and industry professionals seeking to understand the fundamental aspects of epoxy resins and their potential for innovation in various fields.