Aerating your wort is one of the more important steps when making beer. After boiling it for an hour or however long your recipe specifies, nurse
a lot of the oxygen that was in the water has come out. All those bubbles during boiling are water vapor – H2O – a third of which is O, or oxygen. This oxygen is a vital part of the fermentation process, as yeast are aerobic creatures, meaning they need oxygen to thrive and procreate, just like we do.
The problem is how to get oxygen back into the wort.