Yeast is a necessary ingredient in all leavened breads. Not only does it give the bread its "risen", fluffy and doughy texture, it also lends a distinct flavor to the genre known as yeast breads. Bread, rolls, pizza dough, bread sticks, bagels and everything else that requires kneading, poking, rising and baking all require yeast. In most recipes, the yeast must be dissolved and activated before using. This is done most often in water at a specific temperature that is not too hot or too cold.
Check the expiration date on your yeast packet or jar. Yeast does not last forever and if you start with dead yeast it will not activate or bubble. Make sure you are using live, fresh yeast.
Measure the appropriate amount of water needed for your recipe. All dough requires varying amounts of liquid, therefore you must use the amount called for in your recipe.
Heat the water to a temperature between 110 and 115 degrees Fahrenheit. Hot tap water can reach this temperature, but you can also heat the water in a microwave if you prefer. Use a kitchen or candy thermometer to ensure the water is the right temperature (if it is too hot the yeast will die and if it is too cold the yeast will not activate). If you do not have a thermometer, touch the water against your skin; it should be the temperature you would prepare a baby bottle to. If it is too hot, let it cool.
Sprinkle the required amount of yeast on top of the water and let it sit undisturbed. After two minutes, stir until dissolved. Let it sit two to three more minutes while the yeast bubbles and foams up. If it does not bubble after five minutes then it is either dead or the water was too cold. If this is the case, throw it away.
Add ingredients directly to the yeast (as called for in recipe) at room temperature only. Adding milk, butter, eggs or cream that are hot or cold will either kill or shock the yeast and prevent it from rising. Do not add salt to the yeast mixture until after the flour is incorporated or the salt will kill the yeast.