Web is 20 Years Old – Web 3.0 – Third Decade of Web, Officially Begins Posted on March 13, 2009 by Nova The Web is 20 years old this month. The third decade of the Web has started. This means we are officially in Web 3.0 now. Web 2.0 is finished. Read more about this definition of Web 3.0 as the third-decade of the Web, here.