php get variables as key with no value assigned

Question

If I enter the following into the browser:

   http://domain.com/script.php?1234

And script.php has the following script:

Answer 1

This is correct. The variable is called 1234 and it has no value. That means

GET['1234'] == '';

You could as well write http://example.com?1234=10 Then the result would be

GET['1234'] == '10';