Request.ServerVariables is a collection which gives many information about the hosting server, its operating system and the current page being served.
There are many members in it. Some of them are :
1) HTTP_REFERRER - the page which called the current page
2) SERVER_NAME - the virtual directory / host name / DNS alias / IP address of the page being served. If you are using this in a page http://www.yoursite.com/users/welcome.asp
, Request.ServerVariables("SERVER_NAME") will give www.yoursite.com
3) SCRIPT_NAME - the path of current file in relation to host name. If you are using this in a page http://www.yoursite.com/users/welcome.asp
, Request.ServerVariables("SCRIPT_NAME") will give /users/welcome.asp
You can get a list of them from
Request.ServerVariables("HTTP_HOST") will give the name of the host on the server. i.e. www.yoursite.com
in the abobe example.
I hope, with this knowledge, the rest of the code you can understand.