The tenor voice of the string family, the cello can get down very low - to low C - and it has a range of more than three octaves. In a string quartet, the cello is the "bass" voice, the others being taken up by two violins and a viola. The cello has four strings, tuned in fifths.
The cello developed in the 1500s and its design continued to change over the next 200 years as designers tried building taller cellos, or adding a fifth string. By Bach's time the cello was pretty much like it is today. Like the early violin, it was used primarily for dance music at first. But in the 1600s, when it was turning up as the bass instrument in all sorts of ensembles, fine cello soloists (most of them italians) began touring Europe.
Many early cello works were written by cellist themselves. The first non-cellist to write a solo cello piece was J.S. Bach, who wrote the six fantastically beautiful suites for unaccompanied solo cello.
Cello soloists of the18th and 19th centuries typically concentrated on virtuosic technique, like the famous Italian violinists, and were missing the really expressive potential of the cello. It took a Spanish cellist, Pablo Casals, at the end of the 19th century, to show what the cello could really do. Casals was not a flashy player. He played more the way an extremely skilled singer would sing.
Modern cellists like Mstislav Rostropovich and Yo-Yo Ma have the best of both worlds. They can play technically flashy passages with the best of them, but what people really respond to in the cello is its rich singing tone. The best concertos show off both characteristics. Victor Herbert, the American operetta composer, was a skilled cellist who wrote two lovely concertos for the instrument. It was when Herbert played his own Second Concerto with the New York Philharmonic in 1894 that Dvorák, in the audience, was inspired to write his own cello concerto - a true masterpiece.