ABL classes are used to represent users, objects, and systems, which are business entities in an enterprise application. A part of your job as a developer is to come up with a set of classes to model your application. Most of the code that you will write to implement a modern application are implemented as classes.

A class contains data members and methods that are used to provide the behavior for the class and to access the data members of the class. An instance of a class is an in-memory object that contains values for the data members. There can be several instances of a class at runtime, each with its own data.

You will most likely develop a class iteratively. That is, you will start by defining the class and its initial behavior. Then you will modify the class as you further develop the layers of the application or as the application requirements change.

For more information, see Define classes and CLASS statement.