Passing information as part of the URL

Good day,

I have seen some PHP scripts receiving information as part of the URL, for example:

Could you please let me know the name of this technique?
Also, when should I use this?
Finally, I’d appreciate if you could recommend a tutorial for me to learn how to use it.

Thanks a lot!!

It’s a query string.
Query strings are used as part of the url to pass data from a client-side page to a server-side script, typically via a form.
Query strings are composed of a series of field/value pairs. The question mark is used as a separator and is not part of the query string.

Take Google as an example:
If I go to and type in “sitepoint” then click “Search”, on the results page the url will be
This means that when it receives my request, Google’s server will examine the contents of the “q” field, to find out what I searched for.
In PHP you would access this like so:

$searchTerm = $_GET["q"];

The reason Google uses this method is so that searches can be bookmarked.