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 indicated the pronunciation /w/, as in Phoenician.

Latin 'F,' despite being pronounced differently, is ultimately descended from digamma and closely resembles it in form.

When the Romans adopted the alphabet, they used 'V' (from Greek upsilon) not only for the vowel /u/, but also for the corresponding semivowel /w/, leaving 'F' available for /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 the Greeks did not have.

The use of the long s largely died out by the beginning of the 19th century, mostly to prevent confusion with 'f' when using a short mid-bar.