Study Guide Taanit 12 What does "fasting for hours" mean and how does Rav Chisda define this? Is it considered fasting if one does not fast until sunset? Rav Chisda held that it is not a fast and the Gemara brings three sources that raise a difficulty on his opinion. Shmuel says one who accepts upon oneself to fast should accept it beforehand. When? Shmuel says in the mincha prayer and Rav says during the time of mincha  (and it is understood from him that it is possible to even a few days before). Rav Yosef tries to prove from the words of  Megillat Ta'anit that Shmuel is correct but his proof is rejected as there is a debate about the wording of the Megillat Ta'anit. Individual fasts - are the laws severe as in Yom Kippur and Tisha B'av (and public fasts)? On what does it depend? Are there public fasts in Babylonia and what does this exactly mean? Is it possible to postpone an individual's fast to another day if necessary? What is the difference between a fast on a dream and the other fasts? The Mishna explains the severity of the second and third series of public fasts. What is forbidden on these days? What happens if after all the series of fasts (three series - thirteen days of fasting) they did not receive an answer? Why on these fasts is it forbidden to work? They compare, based on a verse in Yoel 1:14 fasts to holidays.