wˌɛn ɐ wˈɛb fˈɔːɹm ɪz səbmˈɪɾᵻd tʊ ɐ sˈɜːvɚ θɹuː ɐn ˌeɪtʃtˌiːtˌiːpˈiː pˈoʊst ɹᵻkwˈɛst, ɐtˈɛmpts tə ɹᵻfɹˈɛʃ ðə sˈɜːvɚ ɹᵻspˈɑːns kæn kˈɔːz ðə kˈɑːntɛnts ʌvðɪ ɚɹˈɪdʒɪnəl pˈoʊst təbi ɹᵻsəbmˈɪɾᵻd, pˈɑːsᵻbli kˈɔːzɪŋ ˌʌndɪzˈaɪɚd ɹɪzˈʌlts, sˈʌtʃ ɐz ɐ dˈuːplᵻkˌeɪt wˈɛb pˈɜːtʃɪs.
When a web form is submitted to a server through an HTTP POST request, attempts to refresh the server response can cause the contents of the original POST to be resubmitted, possibly causing undesired results, such as a duplicate web purchase.