there are several methods for making buttercream, but they all rely on a variety of egg-yolk-and-sugar preparations into which butter is incorporated The yolks are always cooked with sugar in some way, and the mixture is whipped as it cools to make it light
The traditional icing served on every store-bought birthday cake you've ever had It's rich and creamy and is easily colored or flavored, and is used for fancy decorations like shells, swags, basketweaves, icing flowers, etc Since it's made almost entirely of butter (hence the name), buttercream has a tendency to melt in extreme heat, so it's not recommended for outdoor weddings
A light creamy frosting made with softened butter, sugar and egg whites The mixture is cooked, then beaten light and fluffy It can be flavored in many ways and is used as both a filling and an icing