question about $_GET, etc

On my laptop i still have 4.11 apache,linux on it but its just for development. I must be confused about get and post handling. I've been referrencing them in $_GET, etc but I was just working on something and linked to a script by using ?section=duh in the query string,etc Now i thought $duh would be empty since i thought all get and post now got stored in $_GET[duh], but i notice if i echo $duh[0] it will return an 'd' is this normal? thanks! shawn