which is the origin of letter "S"?

Answer 1

Semitic Šîn ("teeth") was pronounced as the voiceless postalveolar fricative [ʃ] (like the sound of the letters sh in ship). The original form may have represented a picture of female breasts. Greek did not have this sound, so the Greek sigma (Σ) came to represent [s]. The name "sigma" probably comes from the Semitic letter "Sâmek" (fish; spine) and not "Šîn". In Etruscan and Latin, the [s] value was maintained, and only in modern languages has the letter been used to represent other sounds, such as voiceless postalveolar fricative [ʃ] in Hungarian and German (before p, t) or the voiced alveolar fricative [z] in English, French and German (in English rise; in French lisez (="read" imperative plural); in German lesen (="to read").

Answer 2

S, 19th letter of the English alphabet. It first appeared in its modern form in the Roman alphabet, as the equivalent of the Greek letter sigma,...

Answer 3

It first appeared in modern form and was taken from the greek letter for sigma.