Unleavened bread is any of a wide variety of breads which are prepared without using rising agents such as yeast or sodium bicarbonate. The preparation of bread-like non-leavened cooked grain foods appeared in prehistoric times.
Jewish matza eaten on Passover
Host and communion wafers made of azymes for celebrating the Eucharist in the Latin Church of the Catholic Church and other Western Christians (Eastern Christians such as the Eastern Orthodox use leavened bread)
A flatbread is bread made usually with flour; water, milk, yogurt, or other liquid; and salt, and then thoroughly rolled into flattened dough. Many flatbreads are unleavened, although some are leavened, such as pita bread.
Homemade flatbread
Pane carasau from Sardinia
Lagana from Greece
Georgian tonis puri