Broadly speaking, it is a flavor liquid. Stocks are derived from boiling and or simmering foods in a liquid to impart their own flavors to the liquid being used. In contrast to other flavored liquids, stocks are unthickened. As such, they tend to be more clear and or translucent.

Stocks can be classified two different ways with regards to their colors. White (or light) stocks are lighter in color and have a more subtle flavor. Brown stocks are stocks that have a darker color and a more rich, robust flavor; generally, the items put into the stock are roasted. Examples of light stocks include the following: (unroasted) chicken stock, stock made from veal/beef raw bones (depending on preparation), really any unroasted food and unroasted bones.

Now, stocks are used as a base for soups, sauces, marinades, and more. Though often associated with (for better or worse) French cuisine, stocks have been around since before historical records. Part of this comes from their versatility.

Aside from the myriad of uses that I’ve mentioned already, there is one more use that I have not touched on at all. A side effect of the preparation of certain stocks, particularly those that use bones, is the formation of something called aspic. Aspic, a gelatin formed from collagen, can be used to form other savory dishes; however, it can also be used as a form of food preservation. In the modern era, aspic is considered old fashioned, but the option is there if you care to explore it.