Final answer:
A class is a programmer-defined data type that serves as a blueprint for creating objects, containing both data (as fields) and code (as methods).
Step-by-step explanation:
A special kind of programmer-defined data type is a class. A class serves as a blueprint for creating objects and can hold both data in the form of fields (often known as attributes or properties) and code in the form of methods (functions specific to the class).
For example, if you are creating a program that simulates a library system, you might have a class named Book, which contains information about each book such as title, author, ISBN number, and methods such as CheckOut or Return.