Upanayana is the Hindu initiation ceremony traditionally associated with giving a boy a sacred thread.
The rite marks entry into a period of religious education and disciplined study. In traditional descriptions, the initiate receives instruction in a sacred mantra and is symbolically accepted as a student by a teacher. The sacred thread, known as the yajnopavita, is worn across the body after the ceremony.
Upanayana is especially associated with the three twice-born varnas in classical Hindu legal and ritual texts: Brahmins, Kshatriyas, and Vaishyas. Historical rules about eligibility and age varied, and actual practice has differed widely across regions, communities, and periods.
The ceremony is often translated as the “sacred-thread ceremony,” but that phrase describes only its most visible feature. Upanayana is also a formal initiation into student life and religious learning. It should not be confused with a Hindu wedding, naming rite, or funeral ceremony.