A miracle is an extraordinary accomplishment which God Almighty brings about at the hands of a Prophet in order to prove his Prophethood, strengthen the faith of believers, and to break the obstinacy of unbelievers.
The universe operates according to fixed laws that God has determined. But for these laws and the uniform character of natural events, everything would be happening in a continuously changing, unstable flux and we could therefore not have found out the Divine laws of nature or realized any scientific developments. Although recent discoveries in atomic physics have made it clear that whatever exists is a wave in continuous motion and therefore it is not possible to say that a second later its existence will be in the same state as it is in now, on the surface everything occurs according to the principles which the ‘classical’ or Newtonian physics established.
Normally, life has its own laws according to which we behave. We need certain amount of food and water to satisfy our hunger and thirst and go to a doctor when we are ill. We use animals to do certain kinds of labor for us but we cannot talk to them. Trees are fixed in their places and neither they nor stones and mountains give us greetings. We act in conformity with the laws of gravitation and repulsion and we do not attempt to rise upwards into the sky without first making calculations based upon those laws.