Mawlid or Mawlid al-Nabi al-Sharif (Arabic: مَولِد النَّبِي, romanized: mawlidu n-nabiyyi, ‘Birth of the Prophet’, sometimes simply called in colloquial Arabic مولد, mawlid, mevlid, mevlit, mulud, among other vernacular pronunciations; sometimes ميلاد, mīlād) is the observance of the birthday of Islamic prophet Muhammad which is commemorated in Rabi’ al-awwal, the third month in the Islamic calendar. 12th Rabi’ al-awwal is the accepted date among most of the Sunni scholars, while Shi’a scholars regard 17th Rabi’ al-awwal as the accepted date.
The history of this celebration goes back to the early days of Islam when some of the Tabi‘un began to hold sessions in which poetry and songs composed to honour Muhammad were recited and sung to the crowds. It has been said that the first Muslim ruler to officially celebrate the birth of the Prophet Muhammad in an impressive ceremony was Muzaffar al-Din Gökböri (d. 630/1233). The Ottomans declared it an official holiday in 1588, known as Mevlid Kandil. The term Mawlid is also used in some parts of the world, such as Egypt, as a generic term for the birthday celebrations of other historical religious figures such as Sufi saints.
Source Used: Wikipedia