The next upcoming the Prophet's Birthday starts on sundown of October 18 ending at sundown on Thursday October 19, 2021.
The day reflects how Muslims can live honorable by holding lectures on Muhammad's life in Islamic institutions or mosques. It is a time to educate non-Muslims the understanding of Islam. It is not to convert to Islam. Often the celebration includes parades, outdoor activities, and communal meals including a birthday cake. Non-muslims are welcome to attend the meals and lectures in the community.
The late twelfth century was the earliest observation of Muhammad's birth. This took place on the 12th day of Rabi'I associated with the beginning of Spring. It was a way to strengthen the identity of Muslim and counteracting the Christian festivities. The holy day was mostly celebrated by the court and ruling class, not the common population.