Mayonnaise (often referred to as mayo) is a condiment originating in French cuisine. It is made by emulsifying eggs, oil and an acidic liquid such as vinegar or lemon juice, and may have herbs, garlic, or spices added for flavor. This is traditionally done by combining the egg and liquid and slowly whisking in the oil. Blenders, mixers, and food processers allow modern cooks to incorporate the oil much more quickly. Mayonnaise may separate and fail to emulsify if the oil is added too quickly or it isn't mixed thoroughly enough.
Commercially prepared mayonnaise is widely available, and more popular than mayonnaise made from scratch.
For those following low-fat diets, lower fat and fat-free versions and substitutes are available.