Introduction to Web 2.0

"The accretion of tiny hacks can numb us to the arrival of the stupendous" - Kevin Kelly - We Are the Web - Wired 13.08

Web 2.0 is an term referring to the ongoing transition to a full participatory Web, with participation including both humans and machines. Web 2.0 is characterized by the following themes:

The Read/Write Web: In which the Web is seen as a two-way medium, where people are both readers and writers. The main catalyst for this is social software, allowing communication and collaboration between two or more people.

The Web as Platform: In which the Web is seen as a programming platform upon which developers create software applications. The main catalyst for this is Application Programming Interfaces, or APIs, allowing communication between two or more software applications.

It is important to recognize, however, that "Web 2.0" is not anything other than the evolving Web as it exists today. It is the same Web that we've had all along. But the problems, issues, and technologies we're dealing with are in many ways different, and so using the term "Web 2.0" is a recognition that the Web is in a constant state of change, and that we have entered a new era of networked participation.

The term Web 2.0 was coined by Dale Dougherty of O'Reilly Media.

Foundation Writings on Web 2.0

Get started learning about Web 2.0 here.

What is Web 2.0?: O'Reilly Media Founder Tim O'Reilly's definitive Web 2.0 article. Tim explains Web 2.0 by example, opposing Web 1.0 companies like Doubleclick with Web 2.0 ones like Google Adsense.

In addition, Tim outlines a set of 8 themes that he thinks are crucial for Web 2.0: Web as Platform, Harnessing Collective Intelligence, Data as the Intel Inside, End of the Software Release Cycle, Lightweight Programming Models, Software Above the Level of a Single Device, and Rich User Experiences.
Wikipedia Entry for Web 2.0: The Wikipedia entry for Web 2.0 calls it the 2nd phase of development of the Web, comprised of technical, social, and economic changes.
Web 2.0 for Designers: Richard MacManus' and Joshua Porter's article on what Web 2.0 means for web designers. MacManus and Porter characterize Web 2.0 as the movement to a read/write web, observing 6 trends that signal a change in how web sites are designed: a move to Semantic Markup, Providing Web Services, Remixing Content, Emergent Navigation and Relevance, Adding Metadata over Time, and a continuing Separation of Structure and Style.
Adam Bosworth's ISCOC04 Talk: Google VP Adam Bosworth characterizes Web 2.0 as rich intelligent clients who share information across the web and deal with richer media (photos, sound, video).

Yet Bosworth says that this is not what's really new. Instead, he points to information overload as a primary characteristic of the new Web, and suggests that the tools we'll create to rate, review, and discuss are the real innovation in Web 2.0.
Why Web2.0 Matters: Preparing for Glocalization: Danah Boyd uses the term "glocalization" to describe Web 2.0. She says Web 2.0 is about making global information available to local social contexts and giving people the flexibility to find, organize, share and create information in a locally meaningful fashion that is globally accessible.
Web 2.0: The Power Behind the Hype: Jared Spool points to 4 major characteristics of Web 2.0: The Power of APIs, RSS, Folksonomies, and Social Networks. He says that though these have been around for some time, our new understanding of them and new tools to work with them allow designers to create fast, cheap iterations of innovative software.
The Amorality of Web 2.0: Nicholas Carr's critical piece on Web 2.0. He characterizes Web 2.0 as the "cult of the amateur", suggesting that the promoters of Web 2.0 venerate the amateur and distrust the professional.
Crucial DNA of Web 2.0: Brandon Shauer breaks up attributes of Web 2.0 into 2 groups. Foundation attributes include User-Contributed Value, The Long Tail, and Network Effects. Experience attributes are Decentralization, Co-creation, Remixability, and Emergent Systems.
Web 2.0 by Paul Graham: Paul Graham sees Web 2.0 as comprised of three main themes: Ajax, Democracy, and Don't Maltreat Users. He summarizes these themes by saying that they all point to one idea: Using the Web the way it's meant to be used.
Web 2.0 Workgroup: A collection of blogs talking about all things Web 2.0. Includes news, technology, design, analysis, and PR blogs. A great resource for anyone hoping to follow Web 2.0 topics.
Web 2.0: Mistaking the Forest for the Trees?: Dave Rogers writes a great piece on how Web 2.0 is about empowering users and suggests that users actually drive the success of Web 2.0, not the other way around.

The Original Web 2.0 Companies

The Four Horsemen of Web 2.0

These four companies known for amazing innovation best demonstrate the essence of Web 2.0. Instead of suffering the fate of the other Dot Coms, they thrived through the downturn by leveraging the principles of Web 2.0. Their success is so widely known that it is now taken for granted, while their databases of customer information have become a growing privacy concern.

Google: Google provides many characteristic Web 2.0 services: Blogger, Adsense, Maps, Search, Base, Gmail, GTalk, Reader, Statistics. Each of these services either exploit the read/write Web or the Web as Platform.
Yahoo: Nearly all of the services that Yahoo provides leverage Web 2.0 principles: Mail, Music Downloads, Movie Recommendations, Shopping, Maps, Local.

Yahoo recently acquired both Flickr and Del.icio.us.
Amazon: Amazon's Affiliates program, Reviews, People Who Bought This Also Bought..., and wish list sharing were early and influential Web 2.0 services. Their new Mechanical Turk service is another Web 2.0 gem.
eBay: eBay provides many buyer and seller services that aim for greater participation. Their API is one of the most successful, and the network effects they enjoy from their large user base are unrivaled.

New Exemplars of Web 2.0

New companies and services embracing the principles of Web 2.0.

These companies are by no means an exhaustive list, but are leading the pack. They provide popular software and services that have proved their worth among the competition.

Flickr: Flickr is a fast-growing photosharing service that provides an collaborative user interface as well as a powerful API to it's content. (Recently acquired by Yahoo!)
Del.icio.us: Del.icio.us is a popular social bookmarking service. Joshua Schacter, the founder, characterizes his service as a way to remember things. (Recently acquired by Yahoo!)
JotSpot: Jotspot provides several services: Jotspot - the Application Wiki, which allows users to create and share wiki-like web pages. JotLive - a live group note-taking application.
37Signals: 37Signals provides several services: Basecamp - a project collaboration tool and Backpack - a collaborative tool to create sharable web pages.
Digg: Digg is a content aggregation service. It provides a mechanism for its many users to "digg" a piece of content, and aggregates them like votes to bubble up the most popular content to its widely-viewed pages. In this way Digg culls the actions of its users to provide value.
Writely: Writely is a web-based service that allows for the creation and sharing of documents in a sophisticated word-processor-like interface.
Feedburner: Feedburner is an RSS publishing service. Sites can direct their readers to a feed at Feedburner instead of hosting it themselves, taking advantage of Feedburner's advanced tracking capabilities to provide insight into who is reading your feed.