Three bows (三鞠躬) is the standard funerary and memorial gesture at tombs and political memorials; one bow suffices for daily formal occasions like graduations or weddings. Replaced kowtowing as the standard formal salutation after the 1911 Republican reforms abolished imperial-era ritual.
usage
Compare 鞠躬 (the verb 'to bow') with 鞠躬礼 (the noun 'a bow as a ceremony'). Use 行鞠躬礼 'to perform a bow' in formal/written Chinese.