When we use Earthing and Bonding?
One of the bonding and earthing example is the watching machine in the kitchen.       

If a washing machine were to develop a ground fault, the current would travel down the earthing path.   Without the earth connection, the metal outer casing of the washing machine could become 'live'.  The principal of earthing is to prevent this situation occurring, by limiting the duration of touch voltages.         

Bonding is a connection of all metallic parts using a protective bonding conductor.  So taking our faulty washing machine above, if you were to to touch it and then touch a metal tap in your kitchen, you would be the earth path and could receive a potentially life threatening electric shock.  The lack of bonding (as well as earthing) would create a chain effect of all metallic parts becoming live in the kitchen.  This would also include all pipework too.  It’s quite a scary scenario which is why earthing and bonding are so essential and why it is important to know the difference between the two.    

Bonding is intended to limit the magnitude of touch voltages while earthing is intended to limit the duration of touch voltages.