Every brewer knows when to add hops in the wort.
You need some for the long boil to bitter the beer, some between 10-20 minutes from the end of the boil for flavor, and a handful at the end of the boil to get the intoxicating aroma into the beer. The hopheads among us even dry hop beer for that extra something in many pale ales. Oh, and of course you can add hops to the mash. Hops in the mash have a history in brewing. I first came upon this concept while trying to make the ultimate Berliner Weiss.