Avinu Malkeinu (Hebrew: אָבִינוּ מַלְכֵּנוּ; "Our Father, Our King") is a Jewish prayer recited during Jewish services during the Ten Days of Repentance, from Rosh Hashanah through Yom Kippur inclusive. Since the 17th century, most Eastern Ashkenazic communities recite it also on all fast days; in the Sephardic and Western Ashkenazic tradition (as well as a very few Eastern Ashkenazic communities) it is recited only during the Ten Days of Repentance. Joseph H.
https://en.wikipedia.org/wiki/Avinu_Malkeinu