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.

its a tricky part to create a php multidimensional array
which will be accessed by javascript function.most of the
time it's confusing.i am going to show how to solve the
problem -

in asp.net application there may be different
server errors like file not found,server error,
etc.when those errors happens default ASP.NET error
page is shown which looks odd and users don't
understand what type of errors occured.to overcome
these problems it's a good idea to use own
error files.

Asp.net caching helps you to create high performance applications.
you can cache objects like DataSets,or your created objects.you can
also do page level caching if you used user controls in the page
if your aspx page includes lots of work.