The Microsoft founder was knighted by the United Kingdom's Queen Elizabeth in a private ceremony at Buckingham Palace.

The honor bestowed on the American multi-billionaire is actually an honorary knighthood, because royal titles aren't formally recognized in the United States. Gates was given the knighthood primarily in recognition of his efforts to improve health and reduce poverty in the developing world. To date, the Bill & Melinda Gates Foundation Global Health program has earmarked nearly $5 billion for the effort.

"I'm particularly pleased that this honour helps recognize the real heroes our foundation supports to improve health in poor countries," Gates said in a statement. "Their incredible work is helping ensure that one day all people-- no matter where they are born--will have the same opportunity for a healthy life, and I'm grateful to share this honour with them."

Gates was accompanied at the ceremony by his wife, Melinda Gates, co-founder of the foundation.

Nominated for the knighthood by U.K. Foreign Secretary Jack Straw, Gates was also cited for his business leadership and contributions. In 2000, the Gates Foundation donated $210 million to Cambridge University to be used toward graduate school scholarships for recipients from outside Britain.

Microsoft employs some 2,000 persons in the U.K. and supports directly and indirectly some 17,000 partner businesses in the U.K., Microsoft said. Some 80 researchers are employed at the Microsoft Research Cambridge laboratory.