What is Web 2.0?

To me, this is a conceptual model describing how to use the web as a platform to design and develop business software. However, the phrase "web 1.0" had been coined during the dotcom era some times in 2000. During those years, this phrase was also used in marketing and turned into a buzzword without any real meaning. Later on, there was a yearly conference with the name "web 2.0" aiming at groups of individuals who are interested in developing software on the web. This word is now used mostly referring to any application that runs the web or runs on the web. The following is the link describing this in more detail.