It is quite common to use Response.Redirect
from an event handler to
redirect the user's browser to a different page. This scenario is
supported from asynchronous postbacks too. In this case, the redirect will
use client-side JavaScript to execute instead of the redirect headers that
are used in the case of synchronous postbacks. Cookies that are set from
the asynchronous postback will be effectively saved, which enables
scenarios like using asynchronous postbacks for login pages.