Ajax is composed of the following web technologies:
- HTML + CSS: displays the information in the browser.
- XML + XSLT: Using the browsers XMLHttpRequest function data can be requested, sent, or changed on the Web server.
Now the question, does Ajax really matter? If you're a web developer, the answer is yes it does. If you're just a web surfer, the answer is still yes.
Ajax allows for the creation of interactive web applications that were not possible before without the use of some external plug-in technology like Flash, Java, etc. If you're just a web surfer, it means that you will be able to use feature rich applications without the use of external browser plug-ins.
To learn more about Ajax, check out a site called 'Ajax Matters'. This web site is one of the primary reference places for this technology.