⁃ There were four fasts instituted by the Rabanan in order to mourn the loss of the Beis Hamikdash.
⁃ They are: The seventeenth of Tammuz, The ninth of Av, Tzom Gedalia, The Tenth of Teves (Tannis Esther was instituted later for a different reason).
⁃ The fast starts at dawn (most say it’s 72 minutes before sunrise).
⁃ If you want to eat before dawn, it’s preferable to have it in mind before you go to sleep. However if you didn’t then you can still eat.
⁃ If you want to eat bread or an eggs worth of cake then you must begin eating at least a half hour before dawn.
⁃ Women can start eating the above even within a half hour of dawn.
⁃ If you feel uncomfortable then you’re allowed to brush your teeth and use mouthwash but make sure not to swallow (keep your head down).
⁃ Showering, listening to music, and shaving/taking haircuts are allowed but not preferred.
⁃ Laundry can be done on a fast day.
⁃ Medicines that don’t taste good can be swallowed.
⁃ If liquids are necessary for the medications then they can be taken with less than an ounce of water.
⁃ If you ate or drank by mistake then you have to immediately stop and you can’t eat any more.
⁃ If you realized that it’s a fast day after you already made the Bracha, taste a small amount of the food so that it won’t be a Bracha levatala.
⁃ Pregnant and nursing mothers don’t have to fast.
⁃ Some say that any mother within 24 months of childbirth doesn’t have to fast. Ask a Sheila.
⁃ If u feel sicker than a normal fast & medicine hasn’t/won’t help, or weaker than a normal fast, or faint, you can break the fast.
⁃ One who can’t focus properly at work should ask a shaila about fasting.
⁃ Children under the age of bar/bas mitzva don’t have to fast, not even for a few hours.
⁃ The fast end at nightfall which is preferably at fifty minutes after sunset and if necessary, 42 minutes after sunset.
⁃ Those that are traveling end the fast based on where they are at the end of the fast not where they were at the beginning of the fast.
