Web 2.0, a phrase coined by O'Reilly Media in 2004[citation needed], refers to a supposed second-generation of Internet-based services such as social networking sites, wikis, communication tools, and folksonomies that let people collaborate and share information online in previously unavailable ways.

The problem is that quite a few people were doing this long before "Web 1.0" came along. Once Web 1.0 came along, it was almost immediately picked up as the medium of choice for most people building this kind of application.

O'Reilly media is late to the party.