[A century of research on bacteriophages].

Bacteriophages have a prominent place in the living world. They participate to our understanding of the living world through three main aspects : (i) the dissection of the most intimist aspects of viral infection molecular mechanisms (molecular biology), (ii) the description and functioning mechanisms of ecosystems (ecology), and (iii) the adaptive dynamics of integrated viral and host-cell populations (evolution). This review looks back at the genesis of these fundamental findings and draws a picture of the most active fields of current research.