Hops are added to beer at two distinct times and for two distinct purposes.

They can be added to the boiling malt in order to give some bitter tastes to the finished product, they may also be added later in the process in the fermentation tank to give aromas to the beer.

In addition to flavouring beer hops add anti-bacterial or anti-microbial effects. This protects the beer from spoilage and helps beer to last longer. The surprising aspect of this is that it adds these effects without hurting the growth of microbial yeast cells.

Hops are also responsible for "skunking" of your beer. When the acids from the hops are exposed to light they chemically convert and produce this off flavour. Keep your beer in cool dark places and be suspicious of clear glass bottles. If the bottles are clear, at least make sure they are in a tightly closed case.

Their are literally hundreds of varieties of hops grown around the world and they all have different tastes. Combine this with when the hops are added and the length of time they are boiled (those added to the brewkettle) and you can begin to appreciate how complex the hopping of beer can become and how many different taste profiles can be developed. Don't forget also that various hop tastes will combine differently with the other ingredients in beer to either compliment, enhance, or deduct from the overall tastes.

So just what kinds of tastes are hops responsible for?
The tastes from hops seem to fall under about three loosely related categories.
Grassy earthy tastes like hay, grass, mould, earth, woods, pine, mint and smoke.
Flowery tastes like herbs, flowers, spices, and even candy like.
Fruity citrus tastes like grapefruit, citrus, apricot, orange, and other fruits.

It's this huge variety of flavours that makes tasting different beer so much fun. The possible combinations seem almost endless and when you keep in mind that the flavours from one hop plant may be different than it's neighbour on the next farm or from what it will produce next season the possibilities just keep adding up.

Besides, it means that the beer I just tried may not taste the same if I buy it again in a few months so I have to keep on trying them all over and over again.