Newton's Third Law of Motion

This is most talked about law in the Newton's Laws of Motion. This law states that:

If a force is applied on a body, it applies an
 equal and opposite force.

This law is also generally stated in short as:

Every action has an equal and opposite reaction.

What is so big deal about this law? In fact, there is. Many of the modern day equipments use this law for their working.

For example a rocket:

A thrust is applied by the exhaust of gasses from the rocket. As a reaction, an opposite force is applied on the rocket, which pushes the rocket forward.

Mathematically, we can say that:

F = -R

Where F= Force applied.
      R= Reaction of Force.