Book excerpt: Since its launch in 2006, Twitter has evolved from a niche service to a mass phenomenon; it has become instrumental for everyday communication as well as for political debates, crisis communication, marketing, and cultural participation. But the basic idea behind it has stayed the same: users may post short messages (tweets) of up to 140 characters and follow the updates posted by other users. Drawing on the experience of leading international Twitter researchers from a variety of disciplines and contexts, this is the first book to document the various notions and concepts of Twitter communication, providing a detailed and comprehensive overview of current research into the uses of Twitter. It also presents methods for analyzing Twitter data and outlines their practical application in different research contexts.