Active dry yeast is the form of yeast most commonly available to noncommercial bakers in the United States. It consists of coarse oblong granules of yeast, with live yeast cells encapsulated in a thick jacket of dry, dead cells with some growth medium. Under most conditions, active dry yeast must first be proofed or rehydrated. It can be stored at room temperature for a year, or frozen for more than a decade, which means that it has better keeping qualities than other forms, but it is generally considered more sensitive than other forms to thermal shock when actually used in recipes. Active Dry Yeast is the original all-natural yeast that has been used by generations of bread bakers. Active Dry Yeast provides ultimate baking activity in all yeast doughs, from low sugar to highly sweetened breads. One 1/4 oz. packet (7g) or 2+1/4 tsp of Active Dry Yeast will rise up to 4 cups of flour.