A prosphora (Greek: προσφορά, offering, or in Demotic Greek πρόσφορον) is a small loaf of leavened bread used in Orthodox Christian, Eastern Lutheran and Greek Catholic (Byzantine) liturgies. The classical plural form is prosphorai (προσφοραί). The term originally meant any offering made to a temple, but in Orthodox Christianity, as well as Byzantine Rite Lutheranism and Catholicism, it has come to mean specifically the bread offered at the Eucharist during Divine Liturgy.

A prosphoron is made from only four ingredients, wheat flour (white), yeast, salt, and water. Salt was not used in early times^[when?] and is still not used in the Greek Orthodox Church of Jerusalem.

Any member of the church who is in good standing, has sufficient baking knowledge, and whose conscience is clean may bake prosphora. Often in a parish church the women will take turns baking the prosphora; in monasteries, the task is often assigned by the Hegumen (abbot or abbess) to one or several monastics of virtuous life.

It is common but not necessary to go to confession before baking prosphora, and the baking often takes place in the morning while fasting. Sometimes, special kitchen implements are used for making the prosphora which are used for no other purpose. There may be special prayers said before commencing, and the baker tries to maintain a religious state of mind throughout, often saying the Jesus Prayer. Usually enough prosphora for a number of services are baked at the same time.

A prosphoron is made up of two separate round pieces of leavened dough which are placed one on top of another and baked together to form a single loaf. This double-loaf represents the two natures of Christ: human and divine. Before baking, each prosphoron is stamped with a special seal called sphragis or Panagiari, usually bearing, among other things, the image of a cross with the Greek letters IC XC NIKA ("Jesus Christ conquers") around the arms of the cross. This impression is baked into the bread and serves as a guide for the priest who will be cutting it.

In the Slavic practice (Ukrainian Orthodox, Russian Orthodox, Bulgarian Orthodox, Serbian Orthodox, etc.) five smaller prosphora are used, in commemoration of the five loaves Jesus used to feed the multitudes. The Greek practice involves one larger prosphoron, in commemoration of the unity of all who share the one "Bread" 1 Cor 10:16–17.

Russian Orthodox monasteries or churches may assign the task of baking the prosphora (Russian: просфора, romanized: prosfora, also prosfira (просвира) to prosforniki (Russian: просфорники) - singular form: prosfornik (Russian: просфорник) or to female prosfirni (просвирни - singular form Russian: просвирня, romanized: prosfirnya).

In the part of the Divine Liturgy (Eucharist) known as the Liturgy of Preparation (Proskomedia), a cube is cut from the center of the prosphoron, and is referred to as the Lamb (Ancient Greek: Ἀμνός, romanized: Amnos). It is this Lamb which is consecrated into the Body, Blood, Soul, and Divinity of Jesus Christ and from it both the clergy and the faithful will receive the Most Holy Eucharist, while the rest of the prosphora which was not consecrated into the Body, Blood, Soul, and Divinity of Jesus Christ is cut up for the antidoron, the blessed bread which is distributed at the end of the Liturgy.