Hops added at the beginning of the boil in order to obtain maximum alpha acid utilisation. Any type of hops can be used for bittering, although those higher in alpha acids will require the use of less hops per unit of beer.

ARE HOPS USED FOR BITTERING AND NOT FLAVORING BEER AND ARE USUALLY HIGHER ALPHA ACID CONTENT AND HAVE THE LONGEST BOIL TIME.

Hops added to the boil with 45 - 60 minutes left. These are responsible for the bitterness of a beer.