The stock is flavorful liquid make by gently simmering bones and/or vegetables. Stock are often called the chef's "building blocks." The application of stock is to making many soups and sauces. The stock is an essential ingredient in many soups and sauces. If you can make a great stock, you can make a great soup and sauce. When preparing stocks, flavor, clarity, and body are most important.
The white stock is a clear, pale liquid make by simmering poultry, beef, or fish bones.
The brown stock is an amber liquid made by simmering poultry, beef, veal, or game bones that have been browned first.
The fumet is very similar to fish stock, this is a highly flavored stock made with fish bones.
The court bouillon is an aromatic vegetable broth used for poaching fish or vegetables.
The glace sometimes referred to as "glaze," this is a reduced stock with a jelly-like consistency, made from brown stock, chicken stock, or fish stock.
The remouillage is a weak stock made from bones that have already been used in another preparation, sometimes used to replace water as the liquid used in stock; remouillage is the French word for "rewetting."
The bouillon is the liquid that results form simmering meats or vegetables; also referred to as broth.
The jus is a rich, lightly reduced stock used as a sauce for roasted meats.
The vegetable stock is usually made from mirepoix, leeks, and turnips. Tomatoes, garlic, and seasoning may also be added to flavor or darken the stock, but tomatoes must be strained with a cheesecloth or filter so that no seeds or skins get into the stock.
I think the stocks are an important part of cooking because it can make soup very delicious. The stock is base for sauces, soups, stews, and braises, also it is important vegetables and grains. If you want to make a delicious soups the stock is indispensable.