Epoxy resins have been widely used for coatings, electronic materials, adhesives, and matrices for fiber-reinforced composites because of their outstanding mechanical properties, high adhesion strength, good heat resistance, and high electrical resistance. The final properties of cured epoxy resins are affected by the type of epoxy resin, curing agent, and curing process. This paper aims to review the synthesis, curing process, and application of epoxy resins.