Let me answer in terms of electronic media for community. The internet and modern telecommunications has changed social networks and socialization greatly. It has opened up our ability to communicate over vast distances at near light speed. We now have many more ways in which to communicate in synchronous time with people at distances. Our asynchronous communication (like message boards and social networking) can now involve many more people than with non-electronic media.
Another advantage to electronic media communication is the anonymity. We can be who we choose to be, or we can allow our strengths to overcome our weaknesses in ways that cannot be achieved offline. For example, a physically unattractive person can allow their personality to shine, without the difficulty of having to overcome people's prejudice against their looks. This can also work to eliminate racial and gender prejudice.
However, the lack of physical connection becomes a disadvantage. Some people who use their physical presence as a form of communication are handicapped and need to learn new tools. Also, some will say that our lack of physical contact in electronic relationships degrades those relationships to being less than human, since humans require a certain level of physical interaction.
Also, many electronic media do not convey nuances of human interaction, including body language, facial expression, and voice tone.
Another disadvantage is that for all our improved breadth of communication (broad distances and broad audiences), we've lost a great deal of depth in our communication. We are losing a depth in our relationships with each other, and the depth of history and self-understanding that came from smaller communication circles.
I hope this helps and is on topic.