What exactly is secondary fermentation and why would someone go through the extra step?
Secondary fermentation is the processes of siphoning off your beer from the initial fermenter into another carboy there by leaving behind the sediment at the bottom of the primary fermenter. The yeast cake at the bottom of the fermenter contains dead yeast, remnants from the malt such as gluten, and any remaining hop particles and resins.
This can alter the taste of your beer by lending yeasty and other rounded flavors to your beer. Some people are especially sensitive to yeasty flavors and it can turn them off from your otherwise tasty brew. The insoluble compounds also have hop resins that can leave your beer with a very harsh aftertaste.
An additional benefit from this process is that it will greatly improve the clarity of your brew. There are other ways to improve clarity for more experienced brewers, such as employing slightly longer boils (75-90 minutes), using wort chillers for a very effective cold crash, or Irish Moss in the last ten minutes of the boil. All of these steps will help coagulate the proteins and beta glucans. This will help produce a more clear beer. To be accurate, there isn't any additional fermentation that takes place during this process. It's more accurate to consider it a conditioning phase.
Next week we will bottle!