The glottal stop is not a separate phoneme in English, though it is one of the allophones of the t phoneme in some dialects (as in Cockney or Brooklynese “bo’l” for “bottle”). It functions as a phoneme in numerous other languages, however, such as Arabic and many American Indian languages. For example, in many dialects of English it can be heard as a variant of the /t/ sound between vowels and at the ends of words, such as metal, Latin, bought, and cut. This is what my research has taught me.