Fed was a consultant（咨询师）and Guido a wine maker. They started their gelato （意式冰激凌） business with no food industry experience. "We wanted to make the best gelato in the world and we didn't know how to make any gelato!" Fed recalls. That did not stop them though and the business has become more and more successful.

The word gelato means "frozen" originally. Since ancient Rome, people have been enjoying cold desserts. Many think gelato is just an Italian name for ice cream. But actually it is a different product. According to Fed and Guido, the difference between ice cream and gelato is the amount of fat in the product. In ice cream you have an average of 17-18% of fat, but with Italian gelato you have 10%.

It was Guido who first came up with the idea. He thought that if they got the best materials, they could make top quality gelato. Fed then put a business plan together and the two decided to go for it. The only rule they had when they started out was to stick to their guiding principle—to try to create the world's best gelato. Their efforts paid off. Sales of their gelato have doubled in Italy every year since 2008. It outpaced （超过）the growth of every other type of iced dessert by some way. The company grows from two employees in 2003 to nearly 700 employees today.

According to a market analysis, Italians' love for gelato will last for the next few years. These two will be happy to learn the news.

The guiding principle Fed and Guido followed is_____.