How to thank God for food.
Birkat hamazon, the blessing after the meal, is also known colloquially as "benching," the English version of the Yiddish term bentshn, which means to bless.
This blessing (which is actually a series of blessings) is mandated for use following any meal in which bread has been eaten, since according to Jewish law, eating bread officially constitutes a meal. Birkat Hamazon can be said sitting at the same table or in view of the same table where the meal was eaten. At weddings or Shabbat meals, it is often said communally.
Reciting the blessing after the meal is a mitzvah written in the Torah. Deuteronomy 8:10 states, "And you shall eat and be satisfied, and bless Adonai your God for the good land which God has given you."
Prior to the Blessing
Before saying Birkat hamazon, many people recite a psalm recalling the destruction of the Temple. On Shabbat and festivals, Psalm 126 is sung, recalling God's promise to return the people of Israel to its homeland. On other days, Psalm 137, which mourns for the Jewish people during the Babylonian exile, is sometimes recited.
When three or more people (for traditional Jews, three or more men) have eaten together, a short back-and-forth invitation, called a zimmun, precedes the prayer. The leader invites everyone present at the meal to recite the blessing, and they respond with words of praise for God. At a wedding meal, additional lines of praise are added.
When 10 or more have eaten together, God's name is added to the zimmun. There is also a custom of saying Birkat Hamazon over a cup of wine when 10 people, or more, eat communally.
The Blessings' Organization
Structurally, birkat hamazon is composed of four blessings. The first blessing, also called birkat hazan, praises God for sustaining life and providing food for all creatures. Often when a group has eaten together this blessing is sung out loud.
The second blessing, birkat ha'aretz, thanks God for being compassionate and nourishing the Jewish people, both with food and with Torah. It recapitulates Jewish history from the Exodus to the conquering of the land of Canaan. The blessing also mentions that just as God sustained the Jewish people in the desert, so too God currently sustains them and will do so in the future. In this second blessing, additional paragraphs are added during Purim and Hanukkah. Today, some Jews add a paragraph for Yom Ha'atzmaut--Israel's Independence Day--here, as well.