But there's a danger to metaphors; no metaphor really provides a complete explanation of anything, but it's a human tendency to stretch them a bit too far, assuming the things we are comparing are more alike than they are. This can lead to bad decisions.
It's can also lead to sheer eye-popping silliness, like this this blog post from Jason Calacanis offering the "official" definition of Web 3.0.
Web 2.0 is a metaphor. There is no real taxonomy of web services placing them into "1.0" or "2.o" categories, and people will debate what makes a site a 2.0 vs 1.0 site, a conversation about as useful as the old saw about angels dancing on the head of a pin. The nice people at Wikipedia - that would be all of us, by the way! - actually provide some wisdom that appears to have flown right over the head of Calacanis and the people he says are asking him for such a definition:
In alluding to the version-numbers that commonly designate software upgrades, the phrase "Web 2.0" hints at an improved form of the World Wide Web. Technologies such as weblogs, social bookmarking, wikis, podcasts, RSS feeds (and other forms of many-to-many publishing), social software, web application programming interfaces (APIs), and online web services such as eBay and Gmail provide a significant enhancement over read-only websites. Stephen Fry (actor, author and broadcaster) describes Web 2.0 as "an idea in people’s heads rather than a reality. It’s actually an idea that the reciprocity between the user and the provider is what’s emphasized. In other words, genuine interactivity if you like, simply because people can upload as well as download". The phrase "Web 2.0" can also refer to the transition of websites from isolated information silos to interlinked computing platforms that act like software to the user. Web 2.0 also includes a social element where users generate and distribute content, often with freedom to share and re-use. The result is a rise in the economic value of the Web as users can do more online.Get that? It's an idea. There was no Web 1.0. There was no Web 2.1 bug fix, Web 2.0 SP 1 service pack, Web 2.5. There will not be a beta of Web 3.0 before its release nor an upgrade path from Web 2.0 to Web 3.0. Moreover, there never need to be any such thing as Web 3.0, unless it becomes a useful metaphor for describing some major shift in the way the web is used.
The problem with stretching metaphors too far is that it's sloppy thinking that leads to sloppy conclusions, and one need look no further than the "offiicial" definition of Web 3.0 to see just how sloppy thinking can get:
Web 3.0 is defined as the creation of high-quality content and services produced by gifted individuals using Web 2.0 technology as an enabling platform.Essentially, it will be Web 3.0 but the people making content will be smarter! That's not a bad dream but as a definition for the next major paradigm shift on the web, it's pretty dumb.
And it's hard not to miss the irony here; after hearing about the "democratization of content," which is a nice way of saying that people with expertise and skills will be displaced by amateurs, it's pretty funny that in the definition Calacanis has come up with is the suggestion that maybe that wasn't the best thing ever.
Web 2.0 is a somewhat useful metaphor (but not nearly as useful as some people think, given how much out there is not clearly old web vs. 2.0 web). Should someone manage to define an actual major change in web use that's so different that it merits a new metaphor, and is really happening among users, a metaphor to describe it would be useful.
Personally, though, I hope "Web 3.0" isn't that metaphor, because it sets us on a path toward someone like Calacanis someday deciding to tell us what Web 4.0 is, and the carnival of silliness will just continue.