The phrase “Web 2.0” was coined by Tim O’Reilly in 2003 and refers to the way software developers are now using the web as a platform for delivering applications to end users and the consequent transition of websites from isolated information silos to sources of content and functionality. It is often referred to as the “participatory web” or the “read/write” web which exploits the many-to-many potential of the internet, connecting individuals to each other. This contrasts with Web 1.0, the “read-only” web of information sources and transactional sites that streamline one-to-many services between producers and consumers.

For a service to be perceived as Web 2.0, the key attribute is that it should enable user participation: both contribution by users and sharing, collaboration or networking between users. Consequently these services are also referred to as being “social” – as in the terms “social software”, “social networks” and so on.

Following are some of the dominant services generally regarded as epitomising Web 2.0.

Blogs are online journals published in a particular format: the home page presenting most recent items (called “posts”) and archive pages presenting collections of past posts, typically by month and category. User contributions are enabled via comments to individual posts.

Wikis are collaborative websites whose pages can be created and edited directly on the web by anyone with access to the wiki. The best known is Wikipedia, with 2 million articles in English currently published. But wikis can be used for the collaborative development of any type of publication – from encyclopedic projects, through dictionaries, text books and other reference works, to individual documents such as draft contracts and policy documents, agendas and so on.

Social networking services focus on the building and verifying of online networks for communities of people who share interests and activities or who are interested in exploring the interests and activities of others. They provide a collection of ways for users to interact, such as chat, messaging, email, video, voice chat, file sharing, blogging and discussion groups.

Social bookmarking is a way for internet users to store, classify, share and search internet bookmarks. The best known service is del.icio.us.

File sharing has been a feature of the internet for many years, pre-dating Web 2.0, initially used for the “sharing” of recorded music and software programs. Now photo sharing services such as Flickr offer a convenient platform for storing archives of digital photographs, for sharing these with friends and showcasing work, and video sharing services such as YouTube host video clips and primarily provide entertainment.

Virtual worlds are computer-based simulated environments in which users interact via “avatars”, ie two- or three-dimensional graphical representations of humanoids. Initially most commonly used for so-called massively multiplayer online games (MMOGs) such as World of Warcraft, virtual worlds are now increasingly used to mirror real-life interactions. Popular examples are Club Penguin and Second Life.

The web as a platform

The participation and collaboration on Web 2.0 sites is made possible because the web is used as a “platform” – ie programs run, and databases are stored, on servers on the internet; anyone can access them from anywhere, and connect and interact with anyone else on the same network, using just a web browser.

In addition to the classic Web 2.0 services indicated above, there are many other services which seek to replace and improve on the commonly-used, single-user or locally-networked office applications. Although they currently lack some of the functionality of their desktop counterparts, these services are attractive as they are available from anywhere and accommodate collaboration and sharing. For example, Google’s Docs & Spreadsheets is a web-based word processor and spreadsheet application which allows users to create and edit online while collaborating in real-time with other users.

Closely related is the term “software as a service” (SaaS) – the model whereby a software vendor hosts and operates an application for use by its business customers using the web as a platform. Customers pay not for owning the software itself but for using it. SaaS is typically seen as a low-cost way for businesses to obtain the benefits of commercially-licensed, internally-operated software without the associated complexity and high capital costs. It is, if you like, the closed, “business end” of Web 2.0. Typical examples of SaaS applications are customer relationship management, video conferencing, human resources, accounting and email.

Tools and techniques

There are many different tools, techniques and technologies that contribute to the functionality of Web 2.0 sites. Here are some of the key ones that are used in many applications and are most responsible for the rapid development of new services.

RSS (Really Simple Syndication / Remote Site Syndication) is a family of standard XML data formats used to publish “feeds” of latest information from news sites, blogs and other databases. A feed contains headlines and links to latest items and either excerpts or the full text of the items. RSS makes it possible for users to keep abreast of developments in an automated manner using a feed reader or aggregator. RSS feeds can also be readily incorporated into others’ web pages, enabling third party sites to publish live information syndicated from the publisher’s site.

Tags are simply keywords or terms associated with or assigned to pieces of information or items. Tags are used in most Web 2.0 services to categorise items and are usually chosen informally and personally by the author, creator or consumer of the item.

Folksonomies are user-generated taxonomies created from tags. Folksonomies are intended to make a body of information increasingly easy to search, discover and navigate over time.

AJAX (Asynchronous JavaScript and XML) is a technique used for creating interactive web applications which avoids the need for entire web pages to reload each time users request a change.

APIs (application programming interfaces) are interfaces that enable programs to use facilities provided by other programs.

Mashups are web applications that combine data from more than one source into an integrated experience. The most common implementations are those built using Microsoft, Google, eBay, Amazon, Flickr and Yahoo APIs. For example, OnOnemap overlays details of properties for sale and other local amenities onto Google Maps.

Trackback is a method by which web authors can request notification when somebody links to one of their documents. Trackbacks are used primarily to facilitate communication between blogs.

(Continued … What’s in it for Lawyers?)