Yeast comes in many forms, but this page will discuss only the 2 most common types used for pan breads. From Active Dry yeast to Rapid Rise or Instant yeast, these 2 dry varieties of yeast work rather quickly when making pan/sandwich bread and when compared to a sourdough or natural yeast starter.
Yeast is the ingredient that allows your dough to rise. Without yeast, you have flat or unleavened bread. Active dry yeast and instant or rapid-rise yeast have the same function when it comes to getting your dough to rise.
Types of Yeast Bread 101
Active Dry yeast - A dry yeast that requires activation or proofing to begin the yeast/fermentation process. Active dry yeast has been around as long as your grandmother - perhaps longer, but real grandma's used sourdough starter. I loved my grandma and her bread was awesome, but things have changed and we don't all keep sourdough starters in the pantry any longer. Active dry yeast was the first of the dry yeasts to help speed up the rising process.
To proof Active Dry yeast:
Simply add the yeast to 1/4 cup of water and a pinch of sugar, give it a stir to disolve the yeast and wait 5 minutes. The yeast will begin to foam and bubble, or proof. At that point, you can add the water/yeast mixture to the other ingredients in your bread.
Rapid Rise or Instant yeast - Years ago, the yeast God's decided that Active Dry yeast wasn't fast enough and besides, it was a bit messy - all that foaming and bubbling and proofing. So they invented Rapid Rise/Instant yeast which causes dough to rise even faster - sometimes up to twice as fast. We all like the taste of fresh bread, but we don't like to wait. Rapid Rise was the answer to the wait game, AND it didn't require proofing. Coincidentally, instant yeast is also the type of yeast used in most bread machine recipes.
How to use Instant Yeast:
Whether in a bread machine or in other recipes, just toss the required amount of instant yeast in with the other ingredients and no worries, it all comes together and rises like a dream. No proofing required. However, time is a friend to great bread. The more time bread is given to rise and ferment, the better the flavor. The time issue applies more to artisan breads which require longer rise cycles, but the flavor of pan breads can also benefit from a slower rise. However, since the flavor of pan bread is usually determined by other ingredients (type of wheat, oils, herbs, sweetners), Rapid Rise/Instant yeast works quite well and makes a good loaf of bread.
Natural Yeast / Sourdough - Using natural yeast, or sourdough starters is a step above standard yeast breads. When you use sourdough as the yeast for your bread, the process for making bread changes completely. Sourdough requires time and patience, feeding, nurturing, remembering, and again, more time.