It is the basis for Coordinated Universal Time (UTC), which is used for civil timekeeping all over the Earth's surface and which has leap seconds.
ɪɾ ɪz ðə bˈeɪsɪs fɔːɹ koʊˈɔːɹdɪnˌeɪɾᵻd jˌuːnɪvˈɜːsəl tˈaɪm jˌuːtˌiːsˈiː, wˌɪtʃ ɪz jˈuːzd fɔːɹ sˈɪvəl tˈaɪmkiːpɪŋ ˈɔːl ˌoʊvɚ ðɪ ˈɜːθz sˈɜːfɪs ænd wˌɪtʃ hɐz lˈiːp sˈɛkəndz.