Challah is a

Challah is a special Jewish braided bread eaten on Sabbath and holidays. According to Jewish tradition, the three Sabbath meals (Friday night, Saturday lunch, and Saturday late afternoon) and two holiday meals (one at night and lunch the following day) each begin with two complete loaves of bread.
The traditional challah recipes use numerous eggs, fine white flour, water, yeast, and sugar. Modern recipes may use fewer eggs (there are also eggless versions) and may replace white flour with whole wheat, oat, or spelt flour.
According to Jewish law and practice, salting Challah is a critical component a blessing over the bread. Salt has always played an indispensable role in Jewish life and ritual. Following the blessing the challah it can either be sliced with a knife or broken apart by hand. Pieces of the bread are then distributed for all to eat.
So it could be said that Challah is a loaf of yeast-risen egg bread that is traditionally eaten by Jews on Shabbat, on ceremonial occasions and during festival holidays. The word "challah" refers to the portion of dough that is traditionally separated from the rest of the dough before baking. The plural of "challah" is "challot."