Bell

Bell, also known as alert is the eighth Unicode character being U+0007, it's located in the Basic Latin block in the Basic Multilingual Plane. Bell is the first C0 command which has minor or no use in transmission, since it's a miscellaneous code.

Main use
Bell is used as a device control code originally sent to ring a small electro-mechanical bell on tickers and other teleprinters and teletypewriters to alert operators at the other end of the line, often of an incoming message. Though tickers punched the bell codes into their tapes, printers generally do not print a character when the bell code is received. Bell codes are usually represented by the label " ". They have been used since 1870 (initially in Baudot code) - Wikipedia

In other words, bell is used as a device control code to send a small ring sound on electric mechanics on the bell of the tickers and other teleprinters and teletypewriters in order to alert operators at the other end, often being an incoming message, however tickers punched the bell codes into their tapes, printers normally don't print a character the alert is received. Bell codes are normally represented " ". And they have been used since 1870, normally and first started in the Baudot code. It is also important to know that bell sounded like a real bell.

Other

 * Since the caret notation for BEL is ^G some keyboards have the g key located with bell labeled