Yom Kippur

Yom Kippur (/ˌjɒm kɪˈpʊər, ˌjɔːm ˈkɪpər, ˌjoʊm-/; Hebrew: יוֹם כִּיפּוּר‬, IPA: (ˈjom kiˈpuʁ), or יום הכיפורים‬), also known as the Day of Atonement, is the holiest day of the year in Judaism. Its central themes are atonement and repentance. Jewish people traditionally observe this holy day with an approximate 25-hour period of fasting and intensive prayer, often spending most of the day in synagogue services.

Question: do you fast on the day of atonement
Answer: yes