Classes are the main building blocks of any object-oriented programming language. The concept of a class was first studied by Aristotle. He was the first one to come up with the concept of a class of fishes and a class of birds. All objects, despite being unique, are part of a class and share common behavior.

A class enables you to create your own type by grouping together methods and variable of other types. Think of a class as a blueprint; it describes the data and the behavior of a type.

Classes are declared by using the class keyword, as shown in the following example:

    class Deposit { 
    } 

Compared to Java, you can define multiple classes within the same source file. The class keyword can be preceded by the access level. If it is not specified, it will default to public; this means anyone can create objects of this class. The name of the class follows the keyword and the curly braces contain the class body where the behavior and data are defined: fields, properties...