Java supports inheritance as it's core functionality and then to achieve a lot of OOPs principles like abstraction using

inheritance.

A class can extend another class using `extends` keyword and can inherit from an interface using `implements` keywords.

The access modifiers define rules for the member variables of a class about their access from another classes(or anywhere in

the code).

There are mainly three access modifiers:

- private

- public

- protected

- Default (No keyword required)

You can read more about them [here][access-modifiers]

These concepts are very similar and are often confused.

- Inheritance means that the child has IS-A relationship with the parent class.

interface Animal() {

public void bark();

}

class Dog implements Animal {

public void bark() {

System.out.println("Bark");

}

}

Here, `Dog` IS-A `Animal`

- Composition represents a HAS-A relationship.

interface Engine {

}

class Car {

private Engine engine;

}

Here, `Car` HAS-A `Engine`

[access-modifiers]: https://www.geeksforgeeks.org/access-modifiers-java/