A rich dough is a dough that is high on fat , sugar, and eggs. thus making the item your making soft and some what cake like sometimes.
Examples: brioche, croissants, Danish pastry.
A lean dough is a dough that has very little or no fat content.
Examples: baguette,hard rolls, pizza doughs, egg breads.
Wild yeast is also called Saccharomyces exiguus (also known as S. minor).
A bread starter is the base for many artisan breads including sourdough and Amish Friendship Bread. It uses naturally occurring wild yeast to raise bread, lending a distinct flavor and texture to the bread which cannot be replicated by commercially harvested yeast.
3 bread starters: sourdough starter,sponge starter.
The starter can be used in a recipe, but must be activated so it is vigorously bubbling before using in a recipe.By making a "starter" in which wild yeast can grow, the sourdough baker can raise bread naturally.