What is a Yeast Starter? Yeast is the workhorse of the home brewing process. It is the yeast that will take your sugary wort and turn it into beer. In many cases, it is the yeast that will also work in the bottle to carbonate your beer. In many beer styles, like Belgian ales, yeast also contributes flavor to the beer. Given the importance of yeast in home brewing, making sure that you pitch a sufficient quantity of healthy yeast into your wort is vital to ensuring that your finished beer is going to be good. When you purchase yeast for home brewing, you'll typically receive either a packet of dry yeast which must be reconstituted with warm water, a tube filled with yeast in a slurry, or a packet that contains yeast and an activation solution in a "break-open" capsule. If you are brewing a relatively small batch, or a lower-gravity beer, and your package of yeast is within its "best by" date, you may not need a yeast starter at all. If your yeast isn...