How are the Nobel Laureates Selected?

Tweet

Nobel Prize is an international award established by the will of Alfred Nobel, who left a fund to provide annual prizes to people who excel and has great contribution in field of physics, chemistry, physiology, peace, and literature. I knew of some Nobel Laureates in different fields. In Literature, Albert Camus, Jean Paul Sartre, Bertrand Russell, William Faulkner, and T.S. Eliot are the representatives. In Physics, we have Marie Curie, Joseph John Thomson, and the famous Albert Einstein. In the field of chemistry, we also have Ernest Rutherford, Hans Fischer, Richard Kuhn, and Sir Robert Robinson. In medicine, we have Ronald Ross and Hans Spermann. For peace, we have the recent Barrack Obama and the saintly Mother Theresa. They are indeed great people because of their excellence in the chosen field. My inquiry arise on how are they selected?