Empirical evidence suggests that networks of personal relations are important in the micro dynamics of labor markets: even in modern capitalistic economies a high share of jobs are filled by social referrals. This paper aims at shedding light on an apparent puzzle concerning the relationship...

In this tutorial we present some basic ideas behind the notion of Small World. We review the state-of-the-art in the field, and put emphasis on some recent developments, in connection with analyzing the structure of the Web.