Sitting shiva is the Jewish method of mourning the dead.
A person has an obligation to mourn for his/her seven closest relations: spouse, father, mother, brother, sister, son or daughter. Shiva (the first seven days of mourning) begins immediately after the funeral and burial. When the mourner(s) return to the shiva house(s), they are served a special meal, the Seudat Havra'ah, which generally consists of bagels and hard boiled eggs (symbolic of the cycle of life).
During shiva, the mourner(s) are tended to by their extended family or the community, reminding them that they are not alone.
There are various restrictions on the mourner--designed to both honor the dead and focus the mourner on beginning the healing process.
Generally, customs for mourning are the same in both Ashkenazic and Sephardic communities. Mourners do not: 1) work, 2) wear leather shoes, 3) wear freshly laundered clothes*, 4) have marital relations, 5) sit on regular chairs--rather, they sit on the floor, cushions or (in Ashkenazic communities) on stools that are less than 30 cm high, 6) greet others with salutations such as “Hello,” “How are you?” 7) leave the shiva house,** or 8) shave, cut their hair or cut their nails.
Mourners are also restricted regarding Torah study. In some communities, mourners only study the rules of mourning, and recite psalms. In some Sephardic communities, it is customary to study the Zohar.
On the seventh day of Shiva (except in special cases when a festival occurs and shiva is shortened), the mourner(s) “gets up” from shiva and returns to his/her daily routine.
*One may wear clean clothes and leather shoes on Shabbat during shiva.
**There are exceptions to this rule.