Best beer season of the year!

[Scotty]

For bottling I just toss in some sugar water, or in the case of this recipe, maple syrup.  The remaining yeast in the beer eats the sugar, and produces just enough CO2 to carbonate the beer.  Add too much sugar and it produces too much carbon dioxide, causing a gusher of beer to fly up in your face.  Too little, and its flat when you drink it.

Unlike fermentation, when the CO2 has an escape, bottling the beer keeps the CO2 contained.  It has no where to go, but back into the beer, creating carbonation.  Simple, really.

[Lingus]

Another good example of patience is letting fermentation complete fully.  I did a ridiculously high ABV beer a little over a year ago (a barley wine, around 17% ABV), and the fermentation methods for it were very... Interesting.  Everything from adding sugar every day it ferments for two weeks, to aerating it with an aquarium oxygen pump for an hour or two before I store it away for fermentation.  The thing is, when you go to bottle your beer, you have to mix in a low amount of dissolved sugar to the mix to reactivate the yeast just enough to produce enough CO2 so that it will carbonate.  I either added too much sugar, which is likely given how intense the fermentation process was, and how much yeast I added in, or I didn't let it ferment fully before going to bottling.  When I went to go crack a bottle, the beer, quite literally, shot out of the bottle like a busted fire-hydrant, going everywhere.  Had I given it more time to ferment, or been more careful with how much yeast I added in to the mix throughout the fermentation, I likely wouldn't have ran into that problem, but hot damn is that funny to pass to your buddy to have him open, even more so if he asks why you chose to given him safety glasses with a bottle opener. 

See that's the kind of reason why I would love to get into brewing. So many different things can happen. It's science that you get beer out of in the end (if you do it right).