this post will show how to create a file in dotnetnuke module
directory and write some data in the file.you can use this
technique in asp.net application too -

sometimes it's needed to check whether there are multiple same
modules in the current page or not to keep one version of the
module or some other checks.

master pages creates a common look in your application.
if we think about the header and footer in our pages,we
create these header and footer in every aspx pages.this
method has disadvantages.if there were any custom page
which dynamically adds header and footer then would be
good.

if you are participating in a project of a
course,assignment,others on c#.net or asp.net
or may be others then you should follow the
steps for finishing the project successfully.

all asp.net handlers implement the interface of IHttpHandler located
in the namespace of System.Web.ISAPI(Internet server application
programming interface) extensions are somehow analogous to Handlers.