What is the reason and the means for shaving the head in Islam, and is shortening the hair sufficient, or is shaving obligatory?

The Prophet's Sunnah indicates the permissibility of removing pubic hair and armpit hair, as this contributes to complete cleanliness and avoids foul odors. Shaving (using a razor) was the prevalent method for hair removal during the time of the Prophet, peace and blessings be upon him. The Sunnah for pubic hair is shaving, and for armpit hair is plucking, though shortening or using other depilatory methods is permissible to achieve the required cleanliness, as the objective is removal.