Most of the snow is gone so it’s time to brew spring beer. I can brew in the winter but the brewery requires too much energy to keep the yeast happy. Happy yeast makes great beer so keeping them in the dark (they like dark) and at the right temperature ensures good beer.
People brew bitter wort, and yeast converts wort into beer. Yeast are a fungi that were unknown at one time except for their actions. They live by decomposing and absorbing organic matter and produce ethanol. As science progressed, Louis Pasteur proved this and created a laboratory process to isolate and grow a single fungus into a thriving colony capable of fermenting a batch of beer or wine.