The following videos give you some good background on Web 2.0, the basket of technologies that makes the Internet truly useful as an interactive mass medium.
An introduction to Web 2.0
First, here's an introduction to why the Internet is different than any other communication medium we have experienced.
The Human Network
Cisco has produced some useful insights into how the Internet connects everything. They call it the Human Network. It changes fundamentally the dynamics of regional economic development.
An Introduction to Weblogs
Weblogs are probably the most familiar technology of Web 2.0. But what are weblogs? Here's a quick answer.
An Introduction to Wikis
OK, so what's a wiki? Like a weblog, a wiki allows you to write directly to the web. With a wiki, anyone can be an author. The opportunity comes in connecting our knowledge together using wikis. You see that in Wikipedia.
An introduction to RSS feeds
Here's a convenient way to keep up with the information flows: RSS feeds. If you're not sure what they are, spend five minutes with this video.

RSS