Fridays are a good time to take a few minutes and step away from the details of day-to-day development and turn instead to the big picture. Fridays are unfortunately also bad days for posting long articles, so you may want to bookmark this and come back to it on Monday.
So what is Web 2.0? Is it merely a convenient catch phrase for an industry that has a vested interest in declaring that it has put the crash behind it and is on to the next big (and lucrative) thing? In a media sense, yes, of course it is. But there is also some real meaning behind the "2.0" -- and that meaning is best illustrated by comparing it to what we had before.
Eons ago people began communicating with each other via speech. This remarkable accomplishment enabled humans to form strong social networks by sharing data with those in their immediate proximity. This is no doubt the most important milestone in human evolution, giving humans the leg up on all other species. But speech was confined locally and thus limited in terms of what type of data could be conveyed, and by how much and how accurately that data could be preserved.
The invention of written text allowed communications to persist across generations, giving us the basis for commerce, science, and the arts. Thoughts and records could now propagate not just through space, but also through time, with a much higher degree of accuracy and permanence. (It is little wonder that the religions that survive to this day are also those that first adopted written canons.)
In the Gutenberg era we learned how to take those written texts and reproduce them on a massive scale. However, the power of authorship was remained in the hands of the very few, for example cementing the power of organized religion by assisting its spread, but centralizing its control. Little changed for centuries -- even half a millennium later, radio and television were an extension of the printing press. A tremendously powerful media -- enough to topple kings -- but still the power to publish and to broadcast was held in the hands of the relative few.
If anything, the telegraph and the telephone were the true communication miracles, allowing point-to-point contact across impossibly long distances, and they brought that power to the people, out of the control of the few. (I have argued in the past, and may some day write an entire book about, how the postal service is a symbol of the greatest human accomplishments.) But these were one-to-one technologies that could never achieve the scale that the Internet would.
While the Internet started growing decades earlier, it was the release of the first Mosaic web browser that heralded in a new revolution. Though it reached its peak in less than ten years, the era of Web 1.0 will be long remembered as a turning point in human society. As we are still deep in the midst of all of the change it is easy to overlook just how profound the Internet revolution really is.
Web 1.0 was the great equalizer. It put everyone on the same playing field. A single individual sitting at a computer in the remotest region of the globe had the ability to publish as easily and as widely as the largest newspapers. While it has taken several years to get to the point where this has become commonplace (for reasons that may be explained in defining Web 2.0), even the earliest days of the web turned the conventions on their head. From private citizens like Matt Drudge to garage startups like Amazon.com, Web 1.0 was the beginning of an era in which the smallest player on the field could have just as much impact as the largest conventional institution.
Yet the technology of Web 1.0 was simultaneously both ground-breaking and surprisingly traditional. It was ground-breaking in the sense that it reduced the cost of data distribution to nearly nothing. Yet it was traditional in the sense that it generally followed the model of the printing press. (Albeit with very, very inexpensive machinery.) It allowed anyone to run their own printing press, and it removed the middle man from the distribution process. Web 1.0 was a revolution in which hundreds of millions of consumers found their way to millions of new producers.
The legacy of Web 1.0 will be felt for years to come. In fact, the vast majority of traffic on the Internet still follows this paradigm. You have an endless number of sites, large and small, that still present their view of the world in a tightly controlled environment -- managed explicitly at all times between the client and the server. For example, if you shop at Expedia or Travelocity you will be able to buy plane tickets, but you will do so reading their content, using their interface, using their shopping cart, all on their web site. Or if you buy something from Best Buy or Dell you are shopping in a store that has virtual walls just as solid and impermeable as the brick and mortar outlets they are making obsolete.
Thus Web 1.0 was the enabling of the small individual to present itself on par with a much larger entity. In fact, those individuals took the form of the larger entities and adopted the same practices and facades. The greatness of this accomplishment can not be overstated, but the best is yet to come.
Before we get to Web 2.0., it is useful to consider what does not characterize Web 2.0. For instance, for all of the love that rich client-side AJAX applications such as Gmail have earned, that alone does not make them Web 2.0. Simply having a Flash or WML interface or a XHTML+CSS homepage is not enough to qualify. In fact, in some cases these sites actually lock in more control over the data and manage the presentation even further.
There is an intermediary stage in between Web 1.0 and Web 2.0. Chronologically, of course, nothing is that linear -- patterns sometimes arrive early, sometimes far before the world is ready for them. There is a tremendous amount of overlap in each of these phases, and nothing is dying off completely.
Web 1.5 was an early tremor that signaled that data, all data, wanted to break free of the tightly controlled environments of before. Web 1.5 was the birth of the web service API. Amazon's Web Services are one of the earliest examples of a large scale web services API with meaningful data. Other major sites followed suit -- EBay, Yahoo!, Google, have all exposed web services that enable people to access the underlying data without being cornered into one particular application of that data. But this alone is not Web 2.0, though it is a very important step in that direction.
Web 2.0 is about giving up control. It is about setting the data free. It is about providing services that work with other people's data. It is about having a valuable resource and making no presumptions about how or where that resource will be used.
There are two traits that characterize Web 2.0 and differentiate it from Web 1.5. First, Web 2.0 APIs tend to be symmetrical and reciprocal in the sense that not only can data be read out via published interfaces, but can it also be written into those interfaces. This is most apparent when the API is REST-based and supports the full HTTP method set of GET, HEAD, POST, PUT, etc. SOAP APIs can also qualify, and the Web Service Description Language (WSDL) is a necessary component for the discovery of such interfaces.
Second, Web 2.0 APIs are open standards with formal semantic meaning. This, more than anything else, differentiates the applications of Web 2.0 from those that came before. For example, the Amazon Web Services APIs are incredibly rich, but in order to use them a client application must be specifically aware of the AWS protocols and formats. Similarly, in order to use Google Maps, a client application must know specifically about, and code specifically to, the Google API.
The real Web 2.0 is an emerging ecosystem that is taking root around the periphery of the Internet. The real Web 2.0 is the semantic web -- an interconnected network of data and services that describe themselves in meaningful and machine-readable terms. Standards such as RDF help form the basis for Web 2.0, insofar as they enable a distributed and shared understanding of the meaning of the data. Rigorous formality is not always necessary, however -- the emergence of micro-formats such as XFN and rel="tag" are part of foundation on which Web 2.0 is being built.
Where Web 1.5 is about exposing the data, Web 2.0 is about giving that data meaning and thereby setting it free. Web 2.0 is the syndication of data, and syndicating it in such a way that anyone, anywhere can use the results. Web 2.0 does not lock the consumer (who also becomes a producer) into rigid use cases -- it intentionally forfeits that control in favor of much greater returns. And Web 2.0 adds semantic meaning to the data so that the interconnected network of consumers and producers can evolve and adapt and thrive as the system grows. And importantly, Web 2.0 is about symmetrical and reciprocal relationships between producers and consumers to the point where the lines become blurred and one becomes the other.
Or another way to say it:
Web 1.0 was not decentralized, it simply had many more centers. Web 2.0 will be decentralized.
So lets take a stab at imagining what Web 3.0 will look like. In a sense, Web 3.0 will be more of the same. This incremental stage will be characterized by our ability to stream media in real-time -- similar to the way that Web 2.0 lets us syndicate much simpler data today. Convergence will extend to include streaming video and audio over interoperable channels. Your handheld mobile device will call the same media APIs that your flat-panel plasma display does. Your iPod will make voice over IP calls just as easily as the in-dash device in your hybrid car does. If Web 2.0 is about the convergence of text and semantic data, Web 3.0 will do the same for all digital media. And, as we've been promising since the earliest days of the revolution, Web 3.0 will finally bring us per-transaction micro-payments on a global scale.
And to go really out on a limb -- what will Web 10.0 be? Most likely, even more along those lines. Imagine a scenario in which any data -- all data -- can be instantaneously streamed anywhere at anytime. Your very experiences, your senses, perhaps even your thoughts, will be broadcast and archived for anyone to download and view. All human knowledge will be publicly accessible -- all music, all art, all media, all things. The distinction between human thought and computer thought will be blurred. We will be part of the network, the network will be part of us. We will be the hive mind, and we collectively will have evolved into something quite unlike anything the world has ever seen.
If you are skeptical about those ideas, consider this: throughout the millennia, communication technology has always moved forward, never back. And when you look at the major milestones, they are grouped closer and closer together over time. This trend is so dramatic that it is apparent that not only are the innovations occurring more rapidly, but the very rate of change is accelerating. (This is rational, as technology begets more technology. I.e., our inventions not only create product, but also help us create new inventions.)
Moreover, each of these advances in communication technology share exactly the same traits. They all allow for more data to be moved from more places to more places. As these trends show no sign of slowing, we would be remiss to do anything other than but look into what was once the realm of science fiction for the only logical possible conclusion.