This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book deals with resources within classical sociological theory that can both addresses features of the contemporary world, such as globalization, and anticipate later theoretical developments. It examines a specific and central category of analytical object as conceptualized by that form of sociology for which it has arguably had most importance, ethnomethodology. Claims for the central analytical importance of practice today are not confined to ethnomethodology. This form of analysis is of crucial significance to an understanding of the constitution of sociological objects for a number of reasons, not least its systematic avoidance of theory construction as normally understood. The networks of information and communication technologies that form a crucial component of the infra-structure of today's global economy, and for some such as Castells constitute defining features of contemporary societies, clearly deserve serious consideration.