I think its too basic a question, but i have left web development for past 4 years
On the server side, you can use any kind of language you want. This book is focusing on PHP for the server side. [ August 22, 2006: Message edited by: Satou kurinosuke ]
You can also use Java Servlets or .jsp to process the requests - print the output with the response.getWriter().write(String) method. Using Servlets is more efficient, but if you're just learning and want to save time use .jsp.