Eggs are such as basic, everyday ingredient that it's easy to overlook their powerful and diverse functions in cooking and baking. Eggs give structure to baked goods (cakes, muffins, pancakes) as well as savory foods like meatloaf. They work as a leavener, thickener and binder in sauces like hollandaise and mayonnaise, and they give smoothness to everything from custards to truffles. On top of all their undercover work, eggs are nutritious and delicious on their own, whether poached, fried, scrambled, or made into an omelet or frittata. See egg yolks and egg whites for their specific uses, as well as prepping techniques.
Eggs are sold in standard sizes: medium, large, extra-large, and jumbo. Most recipes call for large eggs; if a recipe doesn't specify, assume it means large.1 large egg = 2 oz. = 3-1/4 Tbs. (1 Tbs. yolk; 2-1/4 Tbs. white) 1 extra-large egg = 4 Tbs. 1 medium egg = 3 Tbs. 5 whole large eggs = about 1 cup
In recipes that don't call for a lot of eggs, substituting one size for another is usually not a problem. However, as the number of eggs called for increases, the difference in amount will become more pronounced. When substituting a different-size egg, use the equivalents above to figure out the total volume you'd get from large eggs, then use however many eggs you need to reach that volume.
The most common eggs used in cooking are unfertilized hen eggs. Eggs can be brown or white (or even shades of pale greens and blue), which is determined by breed. Fresh eggs are your best bet for flavor, and farm-fresh are a great treat. At the supermarket, check the carton for a date. Though salmonella is rare in eggs, people at risk should not consume raw or undercooked eggs. Pasteurized eggs, available at many markets, are a good alternative in such cases.
Many recipes call for room-temperature eggs. To warm cold eggs quickly, put them in a bowl of warm water.
Store eggs in the refrigerator in the carton in which they came. They'll keep for several weeks, though they're best used within one week.