Pizza Hut, the world's largest pizza chain, with more than 11,000 stores and $10 billion (£5 billion) in annual sales, celebrates its 50th birthday today.

The chain was set up by the brothers Dan and Frank Carney in Wichita, Kansas, with $600 borrowed from their mother. As most restaurants in their home town were either hamburger takeaways or greasy-spoons, they saw potential in an untapped market - the pizza restaurant.

With the help of their school friends and some second-hand equipment, they opened the first Pizza Hut. The Carneys' dream was to make enough money to pay their way through college and earn some money on the side for their family.

Although the restaurant chain may be celebrating its golden anniversary, the business is not as strong as it was a few years ago. Last year, Pizza Hut closed more restaurants in the United States than it opened, which it attributes to circumstances such as leases ending.

Pizza makers are facing a tough time, as cheese and flour prices have risen and fewer people visit restaurants in a difficult economic environment. Pizza Hut has begun updating its look and menu in the US, with the help of plasma televisions and local sports memorabilia and the sale of baked pasta and chicken wings.

Pizza Hut went public in 1970. The first British outlet opened in Islington, North London, in 1973, and restaurants were trading in Japan and Canada in the same year. PepsiCo acquired Pizza Hut in 1977 and formed a joint venture with Whitbread in the UK in 1982. By 1984, there were 50 Pizza Hut restaurants in Britain. In two years the number doubled in the UK and reached 5,000 worldwide.

By 1993 there were 9,000 restaurants in 84 countries and 300 restaurants and delivery stores in Britain. In 1994, 10,000 restaurants were open worldwide. In 1997 PepsiCo decided to focus on its drinks business, and Tricon Global Restaurants, renamed Yum! Brands in 2002, became Whitbread's partner, launching its franchising programme in 2001.

In 2006 Whitbread sold its share of the joint venture, Pizza Hut UK, to Yum! Brands, the owner of KFC and Taco Bell, for £112 million. The chain included 600 restaurant and delivery outlets.

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