With everyone on earth talking about Web 2.0, I decided I needed to at least know what it meant... After some Wiki-ing and navigating around, it all comes down to this: Web 2.0 is a sort of revolution in the Internet where the websites are metamorphosing from mere content delivery tools to interactive user controlled sources of web services.
Phew, that was quite a mouthful. I'll put it in plain English now.
Back in the good ol' days of the Internet, every web page looked like this one: some (hopefully useful) content and a bunch of links. That was all there was to it... Web designing? Who are we kidding? :)
Then, when nobody was noticing, these new stylish additives came to the forefront. Instead of being just frills and laces on the basic HTML content, they became the important parts of the web pages. Anytime you open Gmail or Google Reader, you see that the pages are entirely responsive to you. It looks more like a desktop program than a web page. That is because they use a (relatively new) technique called AJAX. These types of websites, which look more like desktop programs - which interact a lot with us and change their appearance according to our wishes and whims - are the things that make Web 2.0.
Note that it's not the technology that distinguishes these things. Of course, it is the development of new technologies that made these possible in the first place. But what is important to a Web 2.0 app* is that it is user-interactive.
To make things clearer, let's imagine a 1990's website as a shy child going back to Momma (web server) and asking what to do each time we ask a question (make a click)...
Then, a Web 2.0 app is a sociable teenager (I'll call him W2 from now), ready to converse with you and trying to respond to you by himself. He's a much more interesting person, bubbling with energy and eager to grow more and more. That's a Web 2.0 app - interactive, with lots of decision making made on your own computer (rather than at the server), and very interesting..
However, like every teenager, a W2 has his quirks too. Sometimes he thinks he knows too much, and does things you don't want to. For example, some W2 apps make the 'Back' button of the browser effectively ineffective. This is very annoying for people like me, who click a lot of things and switch back and forth between pages. Also, a growing teenager needs a lot of resources - and so does a W2 app, typically needing more memory and processing than an ordinary (good ol') HTML website. And finally, a teenager crashes and breaks a lot of things (some scientist says it's because their bones are growing too fast for the muscles) - and, sometimes, so do W2 apps. With all their dynamically changing memory requirements and all the jugglery they have to do, sometimes W2 gets too tired and dies - leaving our browser and sometimes our system too unusable..
But when all is said, he's only a teenager, and has a long way to go. Signs are that he'll grow up to be a very smart and sociable person, very much adaptable to the society around him. People say he's going to be the Hero of the Internet; let's hope he remains a user-friendly hero...