We take data from html form several times. For this reason we use php code. But before taking data we need to analyze and filter it. In this regard php can help us more. This php code filter slash, spaces and illegal characters before sending to server. If any user sends illegal characters then php will convert those characters to special character such as <, > etc. This will prevent from hacking a server by attackers.
For using it. Just unzip it by winrar or winzip. And then find out filter file , use it.