The new year comes at the end of next week and Web 2.0 has had one rough and tumble ride in 2005. Over the last twelve months so much great Web 2.0 software has been released, tons of thinking and work has gone into the idea (this year's terrific Web 2.0 blogoposium being just a small example), all the while controversy has raged endlessly about the validity of the term. Yet calmer heads have largely prevailed, such Stowe Boyd recently in a clear headed recapping of the hype and anti-hype, just barely coming full circle back to the working term.  And for the best list of Web 2.0 milestones this year, see Richard MacManus excellent Top 10 Web 2.0 Moments of 2005.

So I'd like to end things with a roll-up of all this year's Web 2.0 discussions and explanation.  I know that many folks are still struggling with what Web 2.0 means, are often confused by thinking it's purely a marketing term, or if you're like most folks, you haven't really heard about it yet.  To those, I think this list will definitely help and it's a good refresher for all of us Web 2.0 followers as well.

In the end, I think it all comes down to the explaining anyway.  Great approaches to software have come and gone over the years.  Their success has been often tied as much to hype and public perception as to any real value.  Thus the Internet itself entered the world stage and to a lesser extent Web 2.0.

Here is a list of the best Web 2.0 definitions and explanations I've come across.  Like anything that appears here, it's purely my opinion and as always, you're welcome to add your own at the bottom in comments:

• O'Reilly's What Is Web 2.0 - The famous meme map alone is worth serious study and is the central work defining the interlocking elements of Web 2.0.  O'Reilly touches on Web 2.0 as having more of a "gravitational core" than being a concrete set of technologies.  He also introduces all the major planks of his vision of the next generation of the Web as a set of best practices from the first generation.  A terrific read worth every minute spent on it.  Finish this before starting the rest.
  
• Wikipedia Definition for Web 2.0 - While this entry undergoes near constant revision, I recommend a visit to see what an amalgam of opinionated contributors brings to the table for Web 2.0 definition.  Devoid of hype or even many buzzwords, the entry has become somewhat disappointing but the key facts are present and is also notably lacking in major anti-hype.  In the end, a balanced if slightly boring view produced by a little wisdom of the crowds.
  
• Richard MacManus Defines Web 2.0 in February, 2005 - It's amazing to see how far along things have come when you read the very interesting pieces hyperlinked within.  Richard does a bang-up job rolling up prevailing opinion at the time from around the Web.  He finally settles on Web as Platform for the time being, but of course, the concept would continue to grow.
  
• The "Official" Web 2.0 Compact Definition - Tim O'Reilly realized his 5 page essay would not result in a pithy definition and so he obliged everyone in October with a more compact definition.  While quite the run-on sentence, the definition does capture the essence: "Web 2.0 is the network as platform, spanning all connected devices; Web 2.0 applications are those that make the most of the intrinsic advantages of that platform: delivering software as a continually-updated service that gets better the more people use it, consuming and remixing data from multiple sources, including individual users, while providing their own data and services in a form that allows remixing by others, creating network effects through an "architecture of participation," and going beyond the page metaphor of Web 1.0 to deliver rich user experiences."
  
• A Cumulative Web 2.0 Definition:  Here is an interesting one, if more than a little obtuse.  Incredibly, this is what comes up first in Google when you search on "Web 2.0 definition", presumably because the word definition is in the title and a few people have linked to it.  While technically not inaccurate, it's not very complete either.  I can't help wondering if partial definitions like this are a big part of the problem people are having understanding the concepts.
  
• Jeff Clavier Tries His Hand At Web 2.0 Definition - And does a credible job.  He puts openness of data and services as job #1, then rich application experences, and then low cost of delivery using lightweight programming models and techniques.  A bit of a light definition in my personal opinion but highly accessible.
  
• I Give Web 2.0 Explanation A Try - Though admittedly my description might seem a bit overwrought, I still stand by it.  I havent' seen anything this compelling since the original Web and some of things we're seeing, like the Web 2.0 information ecosystem, will change the world forever.
  
• Paul Graham Weighs In On Web 2.0 - Here is one of the most recent explanations and one of the clearest headed.  While I certainly don't agree with everything he says, it's an excellent antidote to some of the most extreme Web 2.0 hype, while not throwing out the baby with the bath water either.  A must read.

And finally, I'm going to add one last Web 2.0 visualization to the mix.  I find so many people derive much more meaning out of visuals than text and perhaps a slightly more up-to-date graphic will help.  For other truly great Web 2.0 visualizations, I refer you to the blogoposium mentioned above.

Figure 1: A reason why Web 2.0, a complex, subtle, yet practical topic, needs so much explanation.

I'll continue to blog about Web 2.0 for the rest of the year but this will be the end of my recap posts.  And please, contribute more visualizations, articles, and commentary below, this is what Web 2.0 is all about...