An Emulsion is a mixture of one liquid with another
with which it cannot normally combine smoothly. 
Oil and water being the classic example. 
Emulsifying is done by slowly adding one ingredient
to another while at the same time mixing rapidly.
This disperses and suspends minute droplets of one
liquid throughout the other.

These are sauces that are created by
emulsion techniques. 
Common sauces in this group
include Hollandaise and Mayonnaise.
Return to Mother Sauces