Typically, you can buy two kinds of yeast: rapid rising and active dry.
Rapid rising – also called quick rise, instant, or bread machine yeast – is yeast that’s treated so that it could be mixed directly with the flour.
Active dry yeast is more traditional yeast for standard bread recipes. This yeast must be proofed in a warm liquid, such as water or milk, so it can leaven.
Proofing yeast:
1. Place the amount of liquid the recipe calls in a pottery bowl. The liquid should be lukewarm, just above body temperature. Too high temperature can kill yeast. Yeast likes sugar, so dissolve a small amount of sugar in the lukewarm water. Sprinkle east on the water.
2. Stir to dissolve the yeast. Let rest in a bowl for 10 minutes.
3. The east will become active – the mixture will foam slightly and look a little puffy.
4. Once it starts to puff, the yeast is proofed and ready to use. Stir in flour 1 cup at time and proceed with recipe.