OK:
I think I understand what you are asking.
Let's look at this example:
http://inventory.overture.com/d/searchinventory/suggestion/?mkt=us&lang=en_US&term=web+design
When you type (or paste) this into your browser address bar you are going to a particular page AND you are passing certain values via the query string (everthing that is BOLDED above).
The script on the receiving end is programmed to read those values and to use those values while it executes...
However, you cannot (usually) just pass values to a website via the query string and expect it to "operate" the way you want it to, unless it has been programmed to do so...
In php, to pass and read those values being passed in the query string you must use the SUPER GLOBAL array: $_GET.
For more information, please read here: http://www.php.net/manual/en/reserved.variables.php#reserved.variables.get
Hope that helps.