Parameters: Parameters are similar to local variables, but they serve as placeholders for values passed into a method or constructor from outside. They also have limited scope within the method or constructor.
Instance Variables: Unlike local variables, instance variables are declared inside a class but outside any method or constructor. They hold data that persists throughout the lifetime of an object and can be accessed by any instance methods in the class.
Global Variables: Global variables, also known as class-level variables, are declared at the class level and can be accessed by any method, constructor, or block within that class. They have wider scope compared to local variables.