IL law requires all servers/bartenders to get themselves certified.
Lasts 3 years. If you're not sure if yours is still valid, click HERE.
There are many websites to take it online, only takes an hour or so. Below are some popular ones. Not sure yet which one is easiest.
Card anyone that looks young, if you have to question it, card them!
(if it's a sting you're arrested and fined)
This also applies to the GAMING AREA, if you see someone questionable, kindly ask for ID just as you would alcohol.
If you're not sure ask a manager/bartender to double check.