Encapsulation

Instead of directly changing the values, we instead give it an interface to mutate / accessor methods (get and set).

public class Point {
	private int intX;
 
	// accesses intX without touching the private variable
	public int getX() {
		return intX;
	}
 
	// gives an interface to update intX
	public int setX(int x) {
		intX = x;
	}
}

Polymorphism

Overriding functionality to let child objects have different functionality from parent classes
Having several implementations of a method (with different signatures)

Inheritance

Using parent objects which pass down information or functionality to child objects

Abstraction

Fuzzing the implementation of the parent class so that the child class implements the functionality in its own way
Seen with abstract methods and interfaces