Da‘wah (also daawa or daawah; Arabic: دعوة "invitation") is the proselytizing or preaching of Islam.
Da‘wah literally means "issuing a summons" or "making an invitation", being a gerund of a verb meaning variously "to summon" or "to invite" (whose triconsonantal root is d-ʕ-w دعو). A Muslim who practices da‘wah, either as a religious worker or in a volunteer community effort, is called a dā‘ī (داعي, plural du‘āh/du‘āt دعاة).
A dā‘ī, as a person who invites people to understand Islam through dialogue, may be regarded as a missionary inviting people to the faith, prayer and manner of Islamic life.
The term da'wah has other senses in the Qur'an. In sura (chapter) 30:25, for example, it denotes the call to the dead to rise on the Day of Judgment. When used in the Qur'an, it generally refers to Allah's invitation to live according to His will. Thus, when used in the first centuries of Islam, it usually referred to that message and was sometimes used interchangeably with sharī‘a and dīn.
Da‘wah is also described as the duty to "actively encourage fellow Muslims in the pursuance of greater piety in all aspects of their lives", a definition which has become central to contemporary Islamic thought.