F
F (named ef) is the sixth letter in the modern English alphabet and the ISO basic Latin alphabet.
History
The origin of 'F' is the Semitic letter vâv (or waw) that represented a sound like /v/ or /w/. Graphically it originally probably depicted either a hook or a club. It may have been based on a comparable Egyptian hieroglyph such as that which represented the word mace (transliterated as ḥ(dj)):
The Phoenician form of the letter was adopted into Greek as a vowel, upsilon (which resembled its descendant 'Y' but was also the ancestor of the Roman letters 'U', 'V', and 'W'); and with another form, as a consonant, digamma, which resembled 'F', but indicated the pronunciation /w/, as in Phoenician. (After /w/ disappeared from Greek, digamma was used only as a numeral.)
In Etruscan, 'F' probably represented /w/, as in Greek, and the Etruscans formed the digraph 'FH' to represent /f/. When the Romans adopted the alphabet, they used 'V' (from Greek upsilon) to stand for /w/ as well as /u/, leaving 'F' available for /f/. (At that time, the Greek letter phi 'Φ' represented an aspirated voiceless bilabial plosive /pʰ/, though in Modern Greek it approximates the sound of /f/.) And so out of the various vav variants in the Mediterranean world, the letter F entered the Roman alphabet attached to a sound which its antecedents in Greek and Etruscan did not have. The Roman alphabet forms the basis of the alphabet used today for English and many other languages.