instance variable: An instance variable refers to variables declared within a class but outside any method. Each instance (object) of the class has its own copy of these variables.
constructor: A constructor is a special method in Java that initializes objects of a class. It has the same name as the class and does not have any return type.
this keyword:The "this" keyword refers to an instance of an object within its own class. It is used as a reference to access or modify instance variables or invoke other methods within that object.