First, pour off excess fat from the hot skillet. Add a small amount of liquid such as water, wine, liquor, beer, stock or broth, vinegar, or tomato and other juices. Return to the heat and quickly scrape up any browned bits from the bottom and sides of the pan with a wooden spoon. To burn off the harsh alcohol taste, flame any alcoholic liquid by tipping the pan carefully toward the flame until the liquid ignites, or just simmer the liquid for a minute or two. These deglazing juices, slightly thickened, can now be used as a sauce.
Once the pan is deglazed, you can now add another liquid, usually stock, broth, or cream, which is then reduced for a subtler and slightly more abundant sauce. Several liquids can be added in this manner, reducing after each addition. This is called stratification.
Pour a small amount of the sauce from a spoon as it reduces to recognize the perfect napping consistency: A properly cooked sauce will coat the food lightly and evenly.