I still remember very clearly my first encounter with peer review: I was a Ph. D. student in physics and I had written my first paper, submitted it to a journal and - after what seemed to me a very long time - received a reply with the request for few changes and corrections I was supposed to include in my paper before it could be considered for publication. These very simple steps: the writing up of some original research results in a paper, its submission to a journal and the process of the work being read and judged by someone reputed to be an expert in the field is what we call peer review