Jewish Minor Fast Practices
All the minor public fasts begin at sunrise and conclude the same day at sunset (which is marked by the appearance of the first three stars in the sky).
Aside from fasting itself, many of the stringent restrictions that apply on the fasts of Tisha B'Av (the Ninth of Av) and Yom Kippur (the Day of Atonement) do not apply to the minor fasts, including refraining from bathing and wearing leather.
The four minor fasts are: Shiva Asar be-Tammuz, the 17th of Tammuz, the date the Romans breached Jerusalem walls; Asarah beTevet, the 10th of Tevet, the beginning of the siege of Jerusalem by the Babylonians; Tzom Gedaliah, the fast of Gedaliah, which falls on the third of Tishrei, the date a Babylonian governor of Judah was killed; and Ta'anit Esther--the fast of Esther--the 13th of Adar, which is the day before Purim.
What Are the Restrictions?
On minor fasts, the regulations are looser, and thus pregnant women, nursing mothers, and the sick are exempt from fasting. Nevertheless, every one--including those exempt from fasting--are discouraged from indulging in unnecessary pleasures. Even those exempt from fasting are discouraged from regular meals or taking more food than is necessary. The purpose of the fast is to meditate on the meaning of the day and examine one's own sins.
Changes in Litrugy
On these fast days there are a number of additions to the regular daily service and a few variations in the liturgy. Avinu Malkeinu ("Our Father, Our King") is recited after the Amidah at the morning and afternoon services. In some traditions, special selihot (prayers of forgiveness) are added. The same section of the Torah is read during both morning and afternoon services. It is chanted with High Holiday cantillation in order to remind the congregation that fast days call for repentance and good deeds. The reading starts with Exodus 32:11-14, and then the reader skips to Exodus 34:1-10. These sections deal with God's 13 qualities of mercy and God's forgiveness of the pious. Traditionally, some of the lines--Exodus 32:12, 34:6, and 34:9--are read aloud by the congregation, followed by the reader, because these lines, in particular, speak of God's mercy and willingness to forgive.