query parameters passes information between pages. For example of you want to go page 2 of a search you might have Search.aspx?pageNo=2
This thread has a url forums.digitalpoint.com/showthread.php?t=1480182 t is the parameter name while 1480182 is the parameter value, which is the ID # of this thread.
That's reduce overload server by request from ID to ID. Like you could find a thread by ID number instead the permarklinks