Many people know from their own experience that it's not easy to install an Apache web server and it gets harder if you want to add MySQL, PHP and Perl. XAMPP is an easy to install Apache distribution containing MySQL, PHP and Perl. XAMPP is really very easy to install and to use - just download, extract and start.
Ajax is a catchy name for a type of programming made popular in 2005 by Google and other big web developers. Ajax loosely stands for A synchronous J avascript A nd X ML, but that just sounds like techno jargon to many people. In plain English, Ajax can be thought of Javascript on steroids.
