Fig 1. The hand sign for Fa (pitch of F) in solfege.
Fig 2. The notes of F in different octaves on the stave, in scientific pitch notation, and on a standard piano keyboard, with frequencies shown in hertz.
Using a reference frequency of 440 Hz for the A above middle C, and calculated in equal temperament, middle F (F4) has a frequency of 349.228 Hz.
F is also the key of F major.
Finally, F is the note that indicates the bass clef. The line of the pitch of F is indicated in the bass clef by the two dots in the bass clef symbol, which itself is a stylized F.