The violin is the soprano voice of the orchestra family and the most popular stringed instrument. Known for its brilliant high sound, it often carries the melody in the orchestra. It is divided into two sections in the orchestra: first violin and second violin.
The viola is the alto voice in the orchestra family. Known for its milky and soothing sound, it often has the harmony part, but will carry the melody from time to time. The viola, unlike the violin, plays a fifth lower than the violin with their C string, allowing it to get a darker tone.
The cello is the tenor voice in the orchestra family. With its incredible range it can go from very low to very high in its register allowing it to cover both melody and harmony parts throughout a piece. The cello is played seated unlike the violin and viola which are played under the jaw.
The double bass is the bass voice in the orchestral family. Arguably the most important part within the orchestra, the bass gives the orchestra its foundation and keeps the beat throughout the piece. The bass is the lowest sounding instrument giving it a glorious and distinguishable tone.