For nearly 40 years, San Francisco's Kronos Quartet—David Harrington, John Sherba (violins), Hank Dutt (viola), and Jeffrey Zeigler (cello)—has pursued a singular artistic vision, combining a spirit of fearless exploration with a commitment to expanding the range and context of the string quartet. In the process, the Grammy-winning Kronos has become one of the most celebrated and influential ensembles of our time, performing thousands of concerts worldwide, releasing more than 45 recordings of extraordinary breadth, and commissioning more than 750 new works and arrangements for string quartet. In 2011, Kronos became the only recipients of both the Polar Music Prize and the Avery Fisher Prize, two of the most prestigious awards given to musicians. Integral to Kronos' work is a series of long-running, in-depth collaborations with many of the world's foremost composers, including Americans Terry Riley, Philip Glass, and Steve Reich; Azerbaijan's Franghiz Ali-Zadeh; Poland's Henryk Górecki; and Argentina's Osvaldo Golijov. Additional collaborators from around the world have included Chinese pipa virtuoso Wu Man; the legendary Bollywood "playback singer" Asha Bhosle; Inuit throat singer Tanya Tagaq; Mexican rockers Café Tacuba; famed Azeri vocalist Alim Qasimov; and iconic American singer-songwriter, Tom Waits. A non-profit organization, the Kronos Quartet/Kronos Performing Arts Association is committed to mentoring emerging musicians and composers, and to creating, performing, and recording new works. The quartet devotes five months of each year to touring, appearing in the world's most prestigious concert halls, clubs, and festivals. Kronos is equally prolific on recordings, with a discography on Nonesuch Records including Pieces of Africa (1992), a showcase of African-born composers that simultaneously topped Billboard’s Classical and World Music lists; Nuevo (2002), a Grammy- and Latin Grammy–nominated celebration of Mexican culture; the 2003 Grammy-winner, Alban Berg’s Lyric Suite; and Floodplain (2009), spotlighting music from regions of the world riven by conflict.