Newton's Third Law of Motion

“Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first”
Simply put, this law states that for every action, there is an equal and opposite reaction. According to this law, all the forces in nature act in pairs in opposite directions on pairs of bodies. For example, when you throw a ball against a wall, there is a force acting upon the wall from the ball. Similarly, the wall also puts an equal and opposite force on the ball and as a result it bounces off the wall. To take another example, when a man is standing on the ground, he is pulled down by the gravitational force of the earth. Also, the man himself is exerting an equal and opposite pull on the earth. One of the key things to identify here is that the action and reaction force always acts on different bodies.
The type of force we encounter often in daily life is contact force. It is the type of force which acts on two surfaces which are in contact with each other. This force will act on the point of direct contact between the two objects. This is in line with Newton’s third law. Contact forces are of three kinds:

• Normal Force
  
• Frictional Force
  
• Applied Force
  

The contact force we encounter most often is the Normal force. It is the force which prevents solid objects from passing through each other. For example, when you place a book on a table it stays on the table without falling. Even though earth’s gravitational force is pulling the book downwards the book is not falling. This means, the contact force from the table must be pushing it up. This force is called the normal force. Here, the word “normal” does not refer to something ordinary or common. It refers to the fact that force is to the two surfaces in contact with each other.