In Islam, bid'ah (بدعة; innovation) refers to innovation in religious matters. Linguistically, the term means "innovation, novelty, heretical doctrine, heresy". Despite its common use in Muslim texts, the term is not found in the Qur'an.
In classical Arabic literature (adab), it has been used as a form of praise for outstanding compositions of prose and poetry.
In early Islamic history, bid'ah referred primarily to heterodox doctrines. In Islamic law, when used without qualification, bid'ah denotes any newly invented matter that is without precedent and is in opposition to the Quran and Sunnah.
Scholars generally have divided bid'ah into two types: innovations in worldly matters and that of in religious matters. Some have additionally divided bid'ah into lawful and unlawful innovations, the details of which are discussed below.
Introducing and acting upon a bid'ah in religious matters is a sin and considered one of the enormities in Islam that is obligatory to immediately desist and repent from.
Sunni Muslim scholars have divided bid'ah in worldly matters into two types:
Good worldly innovations such as using technology to propagate the faith of Islam.
Innovations that are purely evil—these are forbidden under Islamic law. Examples of this type of bid'ah include alcohol, or, in modern times, the discovery and synthesis of new intoxicants.
"A newly invented way [beliefs or action] in the religion, in imitation of the Shariah (prescribed Law), by which nearness to Allah is sought, [but] not being supported by any authentic proof - neither in its foundations, nor in the manner in which it is performed."
"Carrying out actions which displease Allah Subhanahu wa ta'ala and his messenger" Muhammad. (Muhammad ibn Isa at-Tirmidhi).
"New things that have no basis in the Qurʼan or Sunnah" (Ibn Rajab).
bid'ah is always bad but if a new thing has origins in the Qurʼan and Sunnah it is to be called Bid’ah Logaviyya (verbal innovation), (Ibn Taymiyyah).