Over the course of a Jewish year, there are a number of fast days. Two of these fast days, Yom Kippur (Day of Atonement) and Tisha b’Av (the 9th of Av) are classified as ‘major’ fasts and the rest are classified as ‘minor’ fasts.

‘Major’ fast days are observed from sunset to nightfall the next day, a period of about 25 hours. In addition to fasting, there are some additional restrictions which are observed on major fast days:

• leather shoes, or shoes containing leather, are not worn (traditionally, shoes made of leather were regarded as the most comfortable shoes to wear. Hence, wearing leather shoes indicates a concern for our physical comfort. But a fast day is a time to focus on spiritual matters, not on physical comfort; hence we do not wear leather shoes on a major fast day to indicate that our priority is on spiritual matters.)
• ‘annointing’ is avoided – cosmetics etc are avoided. Again, it is a day to focus on spiritual concerns, not on our physical beings and appearance.
• sexual relations are avoided for the same reason.

The restrictions listed above apply only on ‘major’ fast days and not on ‘minor’ fast days.

However, the one restriction which does apply on both ‘major’ and ‘minor’ fast days is fasting. ‘Fasting’ involves not eating or drinking for the entire period of the fast. It is customary to have a meal just before commencing a major fast (some people also arise early to have an early breakfast before commencing a minor fast). However, those who are seriously ill or have a genuine medical condition are often excused from fasting, even on major fast days. This is because Judaism places a high value on life, and considers safeguarding a person’s life to be more important than observing a fast day. A rabbi should always be consulted to see if a particular illness or medical condition is sufficiently serious to warrant not fasting.

Persons above the age of Bar or Bat Mitzvah are expected to fast. Children under the age of 9 years are not permitted to fast as it is considered injurous to their health and development. Children between the ages of 9 and Bar or Bat Mitzvah usually fast for part of the day as a way of preparing themselves for when they will be older and expected to fast for the entire day.

On ‘minor’ fast days, the fast lasts from sunrise to nightfall – how long this is will depend on the season of the year (summer days are longer than winter days).

The best known of the ‘minor’ fasts are Ta’anit Esther (the Fast of Esther, immediately before Purim) and Ta’anit Bechorot (the Fast of the First Born, immediately before Pesach or Passover). However, there are a number of other minor fast days, including the 17th of Tammuz, Tzom Gedalyah (immediately after Rosh haShanah), and the 10th of Tevet. In addition, rabbis may declare a ‘one-off’ fast day in response to some great emergency. Such a fast was declared, for example, at the time of the Six Day War (in 1967). Finally, there is a custom for a bride and groom to fast on the day of their wedding (prior to the actual wedding) as a form of spiritual preparation.

With the exception of Yom Kippur, which is commanded in the Torah, all fast days are rabbinic enactments – observances which are commnded by the rabbis.