Chapter 1 - Introduction

Abstract

In this chapter, we introduce the concept of ‘social network’, and we provide an intuitive and sharp distinction between ‘offline’ and ‘online’ social networks. Then, we describe the main features of Facebook and Twitter, the two online social networks (OSNs) discussed in this book. We show how they are actively contributing to the cyber-physical world convergence, and we motivate the need of novel analyses on the structural properties of OSNs. These are important for understanding human social behaviour in general, and for the creation of novel online social networking platforms that are more centred on human social needs. In particular, the analysis of personal social networks of individuals (called ‘ego networks’) in OSNs can tell us the extent to which the use of social media is impacting on the capacity of humans to socialise. We introduce the main results found for offline social networks, which indicate that the structural properties of ego networks are determined by the constrained nature of the brain, according to the social brain hypothesis. Then, we present the aim and structure of the book, which is to provide an extensive discussion about the structural properties of ego networks in Facebook and Twitter, and to assess the effects of cognitive limits of the human brain on OSNs.