Ibu

[Machine]

I know that the higher the ibu the more bitter it will be but could somebody explain more what ibus are and how they effect the beer.

 

[Mishkin]

ibu's aren't a physical thing. it's a measurement of how bitter a beer is and you can affect the ibu of a beer by amount of hops and how long you boil them.

 

[chillHayze]

http://en.wikipedia.org/wiki/International_Bitterness_Units_scale

 

[david_42]

IBU is just the scale used for bittering, just as we measure the distance to the LHBS in miles or kilometers. Bittering comes from the alpha and beta acids in the hops. The wiki is a bit simplistic, since there are as many as 12 bittering components in an ale.