There are many Server side scripts available in the market and two of them are being used most. One of them is PHP and the other is ASP.NET by Microsoft corporation. PHP is used most by most of CMS (Content Management System).
One of its greatest feature is that it is platform independent means that it can work on any operating system including Windows and Linux. Also it is much easier to learn as compare to other service side scripts.
If you are one of those desperate people who want to learn PHP, we recommend you to watch PHP training series by Lynda. That is PHP with MySQL Essential Training. Author of this series Kevin Skoglund teaches in a great details. There is no doubt that it is the best resource to learn PHP at home in a most efficient way.