ABSTRACT
Online social networks (OSNs) are among the most popular services on the web, which are regarded as a great source of news and entertainment. With the increasing attention drawn by social networks, more and more social network platforms and applications appear and grow rapidly. This chapter discusses the characteristics of population growth in OSNs, and several classical growth models, as well as how the population growth in OSNs fits the classical growth model. It explains the Renren and Twitter data sets by crawling from their sites accordingly. The chapter deals with randomly selected users from the largest weakly connected component in Renren and Twitter, respectively. It addresses the population distribution and the population growth in OSNs. The chapter considers the population size in OSNs is a power-law distribution, with a power-law exponent from 1.4 to 1.8.
