in your example (since you didn’t specify any actual page) http://www.example.com/?id=63 id becomes a variable in your default page (probably index.php). Generally accessible by using the GET method.
You can access it’s value by using the superglobal of $_GET[‘id’] which would contain the value of 63.
Everything AFTER the ? is part of the query string. In the form of variableName=Value To pass more than ONE variable you separate them with the Ampersand (&) sign Var1=Val1&Var2=Val2&Var3=Val3
Also accessed by your script by using the superglobal $_GET[‘VarName’]
A problem will arise (error messages) if you try to get a variable and none was passed. For example if, in your script you look for $_GET[‘id’] and the page was navigated to without using the ?id=63 you will get an undefined index.
You need to just check to see if it’s set first (isset() and then make the logic based upon the result.