The bass is the lowest-pitched and largest instrument in the string family. It is often referred to as the Double Bass, Upright Bass, Contrabass, or String Bass. Its very low tone creates the foundation for orchestral music.
A bass player usually sits on a high stool or stands when playing. The bass can be played with a bow or plucked with the fingers, depending on the desired sound. Whether plucking or bowing, the strings vibrate to create sound. The hollow wood body of the bass amplifies the string vibrations. The player changes notes by depressing strings with their left hand, in effect shortening the vibrating length of the string.
Basses are tuned E-A-D-G, with E being the lowest string.
The easiest way to check that your bass is in tune is with a digital tuner. Most models produce a drone pitch for tuning by ear. These tuners also have a display that indicates whether the string is sharp, flat, or in tune. If you don't have a digital tuner with you, you can use a pitch pipe, piano, or virtually any other instrument to produce the pitches you need. Some players prefer to use a tuning fork.
Basses are tuned by turning the pegs the strings are wrapped around. Tightening the string raises the pitch; loosening the string lowers the pitch. Many basses also have fine-tuners mounted on each string near the tailpiece. With these, the tension of the string can be adjusted more gradually by turning the small screw. The player can use a fine tuner to adjust the string even more precisely by turning the small screw.