Stock (food)

Stock in cooking (cuisine) is a liquid flavoring base for soups and sauces. It is a flavoured liquid preparation, and is the basis of many dishes. The ideas go back to Carême, and were simplified by Escoffier. 
A stock is made by simmering animal bones and/or meat, fish, or vegetables in water and/or wine. mirepoix or other aromatics are added for more flavour. Mirepoix is a mixture of onions, carrots, celery, and sometimes other vegetables. Many use ready-made ingredients like Oxo cubes or bouillon cubes. It is possible to make stock more quickly with a pressure cooker.
Fish stock, however, is cooked for only twenty minutes or so. 
Stock lasts for three or four days in the fridge, but can be boiled again, and stored again.