One of major reasons sociology came into existence was an attempt to explain the shift from rural agrarian society to modern society. Then, as the world advanced even more, sociologists had a new task: to explain the changes taking place in the post-industrial era. Post-industrial really doesn't mean "after industry", it just really signifies the new industries that have come into being along side of traditional factory production. These new industries are computer technology, telecommunications, media and information processing (to name a few. Try and think of some more). These industries function unlike traditional industrial industries (auto, machine, building, textile, etc) because a) their product is different (ie, symbolic goods and services, not hard) b) some of the post-industrial professions involve more educated workers (white-collar as opposed to blue-collar) and c) production can take place in a number of different places (ie, not in a factory).
The question you are faced with explores the impact that "post-industrial" society has on communication and social group operation. Well, try and think how people meet each other now. You can form secondary groups (identity communities or friend groups) through the internet and never meet people face to face. you can keep in touch with primary group members (family and close friends) over the telephone and email and through sending video tapes. Because of airflight, people move around a great deal more. Because of the organization of post-industrial work, people move their primary residences around as companies merge, fold, transfer or whatnot. How does this mass circulation affect the ways in which people associate? How has if affected the family? What does all these cell phones, fax machines, computers do to face-to-face communication and community?