Barley sugar is a type of hard boiled confectionery that is usually made from sugar, water and cream of tartar. This sweet treat has been popular for centuries and is often associated with traditional British confectionery. However, there are several other names for barley sugar that are used around the world. In France, it is known as sucre d'orge, while in Italy it is called zucchero filato. Other synonyms for barley sugar include rock candy, clear toy candy and crystallized sugar. Regardless of what it is called, barley sugar remains a beloved candy that continues to be enjoyed by people of all ages.