Its form stems from the letter "F"; which, in the ancient alphabetical notation system, indicated the note F. It can be inserted into either the third or the fourth line. When situated on the third line it is called baritone clef. Its position is clearly defined by two dots above and below the third line.
Example:
When situated on the fourth line it is called bass clef. Its position is clearly defined by two dots above and below the fourth line.
Example:
The corresponding F sound for both clefs is the one for the third octave of the piano, also called F2.
The F-clef is adopted by all the instruments with a grave extension (violoncello, bassoon, contra-bassoon, bass trombone, bass horns, etc.) as well as keyboard instruments, such as piano, clavichord, etc., which make use of the triple pentagram system.
The F-clef is also used for vocal music for texts for Baritone and Bass voices.