What is the Web 2.0?

Definition

The term has been coined and defined by O'Reilly for designating the use of technologies that improve the design of Web site, allows for collaborative work, create a social networking. New tools allow to concentrate on the content that is managed automatically. Web application and Web service become a bigger part of the industry.

Examples

New kinds of activities and enterprises are appearing: Skype, EBay, Orkut, Second Life, and so ones...

Technologies used by the Web 2.0

These technologies are often combinations of older technologies for new uses, that change completely the appearance and functions of websites, just as chemical is made of combinations of molecules into new materials.

Ajax

Ajax is comprised of JavaScript, CSS, DOM and the XMLHttpRequest object for an asynchronous interaction. Perhaps the main component of the Web 2.0 as it allows to build Web application having the behavior of desktop ones.

PHP and server-side languages

Server-side languages allows to turn web pages into online applications and to use web services.
PHP is the most frequently used and the simplest for small applications. Java and .NET are alternatives.

Mashup

A mashup is a combination of APIs provided by a site or different sites to build new services.
The most usual example is the combination of Google Maps API and the catalog of real state agency to allow customers to visit virtually an apartment and the surroundings. This is used also for restaurants, shops, gas stations and other services. Programming a mashup requires only JavaScript. Alternatively you can use Mapbuilder, define some locations and generate the code. See at resource for a list of mashups.