This is brown stock. It is usually made by the roasted bones. There could also be meat in the stock too. Some bones might be too soft that the bones will dissolve in there and make the stock very musty,
This is a fumet also known as a fish stock. This is used with fish bones and fish to get the flavor. The bones are a little sensitive thats the bones could start to dissolve and make the it very foggy. This is used for flavoring
This is a court bouillon or also known as a vegetable broth. This is made to make the vegetables soft or for flavor. This is made when you just put ion the aromatics.
This is a glace. it more used as a dipping sauce or something that uses it for a coating. It is very much like a jello. Its made from all kinds of stocks that have meat in them.
This is known as a remouillage. it is a weak stock that is made from bones that have been used in another preparation. It is sometimes used as a replacement for water.
This is made from simmering vegetables and meats together. In the spanish culture it is called a caldo. It is a type dish that is served directly from the pot. This is able to have any kinds of poultry, beef, and fish, which is what is mainly used.
Why theyre important, they important so they can be used as a dish or to give food flavor. It is also used to make certain foods softer and more flavorable to eat.