From what I know, Web 2.0 is a term used to represent a shift in how people use technology to communicate and interact with information resources on the Internet. It is about potential, discovery, and sharing.
Human connection and sense of belonging power the interest.
Web 2.0 finds root in the human interest to communicate and share experience. Advances in technology allow us to connect to the Internet and computers in more and more ways. We connect and interact, weaving information sharing into our lives. Not just because it’s increasingly easy.
Developers on the backs of giants: AJAX, DHTML, CSS, HTML, XML
With the widespread realization that JavaScript has server and DOM access at the same time, innovations in web applications are like comparing telephone to telegraph.
User experience getting deserved attention.
Because of these innovations, adherence to standards, and in part, the open source movement, user experience is getting deserved attention because developers don’t have to start from scratch. With so many competitors, user experience and content become the discriminator and strategic advantage for securing attention and interest online. These same innovations provide developers new ways to observe and improve the human-computer interaction.
We are learning from each other.
As data is gathered and studied about how people interact with others online, patterns and behavior similar to communities and social systems are finding ground where there isn’t one. As people with similar interests and information needs discover and invent ways to share perspective, opinion, and thought, technology is there recording it all. Everything shared online, explicity or incidentally, becomes part of a vast miscellaneous collection of data ready to be searched, categorized, tagged, and studied in nearly infinite ways.