The concept in programming that refers to reusing code through the creation of classes is known as object-oriented programming (OOP). In OOP, classes act as blueprints for creating objects, encapsulating data and behaviors within a single structure. This approach promotes reusability, maintainability, and a clear organizational structure in software development by enabling developers to define attributes and methods once and reuse them across multiple instances. OOP principles also support code abstraction and inheritance, enhancing software design.