WorldCat is a union catalog which itemizes the collections of 72,000 libraries in 170 countries and territories which participate in the Online Computer Library Center (OCLC) global cooperative. It is built and maintained collectively by the participating libraries.

The catalog was created in 1971 and, as of April 2012^[update], it contains more than 264 million different records pointing to over 1.83 billion physical and digital assets in more than 470 languages. It is the world's largest bibliographic database. OCLC makes WorldCat itself available free to libraries, but the catalog is the foundation for other fee-based OCLC services (such as resource sharing and collection management). WorldCat was founded by Fred Kilgour in 1967.

In 2003, OCLC began the "Open WorldCat" pilot program, making abbreviated records from a subset of WorldCat available to partner Web sites and booksellers, to increase the accessibility of its member libraries' collections. In 2006, it became possible to search WorldCat directly at its website. In 2007, WorldCat Identities began providing pages for 20 million "identities", predominantly authors and persons who are the subjects of published titles.

Yusuf Islam (born Steven Demetre Georgiou, 21 July 1948), commonly known by his former stage name Cat Stevens, is an English singer-songwriter, multi-instrumentalist, educator, philanthropist, and prominent convert to Islam.

His early 1970s record albums Tea for the Tillerman and Teaser and the Firecat were both certified triple platinum in the United States by the RIAA. His 1972 album Catch Bull at Four sold half a million copies in the first two weeks of release alone and was Billboard's number-one LP for three consecutive weeks. He has also earned two ASCAP songwriting awards in consecutive years for "The First Cut Is the Deepest", which has been a hit single for four different artists.

Stevens converted to Islam in December 1977 and adopted the name Yusuf Islam the following year. In 1979, he auctioned all his guitars for charity and left his music career to devote himself to educational and philanthropic causes in the Muslim community. He has been given several awards for his work in promoting peace in the world, including the 2003 World Award, the 2004 Man for Peace Award, and the 2007 Mediterranean Prize for Peace. In 2006, he returned to pop music with his first album of new pop songs in 28 years, entitled An Other Cup. He now goes professionally by the single name Yusuf. His most recent album, Roadsinger, was released on 5 May 2009.