S is the nineteenth letter of the modern Latin alphabet. Its name in English is pronounced ess /ɛs/.
In most writing systems using the Latin alphabet, as well as the International Phonetic Alphabet, the letter s corresponds to a voiceless alveolar sibilant. Two notable exceptions are Vietnamese and Hungarian, where it represents the postalveolar /ʃ/, as in the English words "sugar" and "sure". Other languages, including English, Portuguese and German have words wherein "s" represents the /ʃ/ sound, but this orthography is considered atypical.