Royal Icing is a type of icing made from egg whites and powdered sugar. It is known for its smooth, hard finish, making it ideal for decorating cookies and cakes. Once dried, it forms a solid layer that can be easily piped into intricate designs. This icing is commonly used in cookie decorating, especially during holidays and special occasions. It can be colored and flavored, allowing for creative expression. Additionally, Royal Icing is often used in gingerbread house construction, as it acts like glue to hold the pieces together.