Distribution of these audio segments is strictly prohibited.
The viola is sometimes thought of as the Rodney Dangerfield of the orchestra, but is gaining more respect from composers who are now utilizing its dark sound in more varied ways. It is the alto member of the family of string instruments which includes the cello and the violin, which it closely resembles. The viola got its start early on with the violin, in the mid-1500s. Since the 17th century it has been the vital middle instrument in string ensembles. Mozart did much to develop its potential in chamber and solo music, most notably in his two-viola quintets and his Sinfonia Concertante for violin and viola.
The 19th century saw considerable exploration of the viola’s possibilities in orchestral music. Wagner, Tchaikovsky, Brahms and Dvorak (who was a violist) all use the viola section of the orchestra for extended melodic passages.
As with the other instruments of the string family, the bow is what gives the instrument its singing quality. Without it, one could only play pizzicato (by plucking the string). Considerable time is spent in a string player’s training learning the fine art of bow technique.
Source: The Norton/Grove Concise Encyclopedia of Music, edited by Stanley Sadie. London: Macmillan Press Ltd.,  ISBN 0-333-43236-3