Supplication (also known as petitioning) is the most common form of prayer, wherein a person asks a supernatural deity to provide something, either for that person who is praying or for someone else on whose behalf a prayer of supplication is being made. One example of supplication is the Christian ritual of novena (from novem, the Latin word for "nine") wherein one repeatedly asks for the same favor over a period of nine days. This ritual began in France and Spain during the Middle Ages when a nine day period of hymns and prayers led up to a Christmas feast, a period which ended with gift giving.

In Islam, the Arabic word du'a is often used for supplication. Du'a may be made in any language, although there are many traditional Islamic supplications in Arabic, Persian and Turkish.