Most recipes call for active dry yeast. Generally, you’ll need to activate the yeast by dissolving it in water before adding to your flour. In the last few years, commercially available active yeast allegedly does not need activation, but I recommend doing it anyways just in case. You can easily sub instant yeast for active dry (I do this all the time!); 1 teaspoon active dry yeast = 1 teaspoon instant yeast. As a bonus, you don’t need activate it — it can be directly added to dry ingredients. If you happen to have fresh (cake) yeast, you can use it as well. This also does not need to be activated and can be crumbled into the dry ingredients or dissolved in water if desired. To substitute for active dry yeast, add in double the amount the recipe calls for (ex: 1 tsp active dry yeast => 2 tsp fresh yeasts) If you have RapidRise yeast, you will have to be more careful. This form of yeast does not do well for longer rises and will not fare well in the fridge. I don’t recommend using this for pizza dough.