The history of the cello can be traced back to the late 16th century and evolved from a 15th-century instrument called the "bass viol" or "knee viol". The viol is not as large as a cello, and its arc is not as obvious, but it can be played between the knees and played with a bow like a cello. The applied clef of cello is bass clef or alto clef or tenor clef. Its structure is similar to that of a violin, but its body is much larger, its bow is slightly thicker and shorter, and its tuning is an octave lower than that of a viola. The body of the instrument is made of wood and is made of maple and spruce as raw materials for the best sound. The strings are made of metal wire and the bow is made of horsetail. The cello is a lower-medium instrument in the cello family. It has a rich and full tone and a cheerful personality. It is good at playing lyrical melodies and expressing deep and complex emotions. Known for its warm and rich tone, the cello is one of the most common instruments in symphony orchestras. It is suitable for playing various roles: sometimes it joins the bass camp and releases a heavy sigh in the lower part; sometimes it plays the role of the rhythmic backbone with the two middle strings. The cello's most glorious moment comes when the composer gives it the mission of expressing cantabile melodies. The entire cello section produced a melody that dwarfed any other instrument in the symphony orchestra.

The body of the cello (Cell) is twice as long as the violin. Its four open strings are an octave lower than that of the viola. The sound is more solid and full, and the timbre in the high range is magnificent, like a heroic temperament. tenor. Because of its beautiful and sincere sound, the cello is often used as a solo instrument and is also an important instrument in ensembles and orchestras. The first theme of the second movement of Tchaikovsky's Sixth Symphony is a waltz in five beats. The melody is soft and elegant. It is played by the cello. It is deeply touching. The theme of the fourth movement of Beethoven's Ninth Symphony, "Ode to Joy," is played from the depths of the orchestra in mute sounds by the cello and double bass without any accompaniment.

Double Bass, also called "double bass", is the largest bowed string instrument with the lowest range. There are three or four strings, and the open strings are separated by fifths or fourths. The pronunciation is deep and powerful, like a bass. Often serves as the bass foundation for the overall sound in the band. It plays an important role in orchestral music. The double bass usually plays the bass part, but sometimes also plays the melody. For example, the fifth piece "Elephant" in the "Carnival of the Animals" suite by the French composer Saint-Sa?ns has a deep and powerful melody played by the double bass, describing the solemn gait of the elephant, which is very expressive.