Ocean10000 - 2:06 pm on May 21, 2012 (gmt 0)

The Query string collection is a name / value collection, which assembled from the values after the ? in a url.

http://example.com?id=1&Sessionid=1000001

The query string collection in this case will have two name/values pairs in it.
Id=1
Sessionid=1000001

Reference:
Request.QueryString Collection [msdn.microsoft.com]