Thread Ceremony of Anshu Triwedi in 2001

In Hindu traditions, a human being is born at least twice — once at physical birth and second at intellectual birth through teacher's care. The first is marked through the Jatakarman sanskara ritual; the second is marked through Upanayanam or Vidyarambha rites of passage.[13][14] A sacred thread was given by the teacher during the initiation to school ceremony and was a symbolic reminder to the student of his purpose at school as well as a social marker of the student as someone who was born a second time (dvija, twice born); he went about collecting fire wood in forest and food donations from villages on a daily basis.[15][16]

Many medieval era texts discuss Upanayana in the context of three varnas (caste, class) — Brahmins, Kshtreyas and Vaishyas.[8] Several texts such as Sushruta Sutrasthana, however, also include Sudras entering schools and the formal education process,[17] stating that the Upanayana samskara was open to everyone.[5][9] The Baudhayana Grihya sutra in verses 2.5.8 and 2.5.9 states the teacher to "[l]et him initiate [to school through Upanayana] a Brahmin in spring, a Kshatriya in summer, a Vaishya in autumn, a Sudra in the rainy season; or all of them in the spring."

The ceremony was typically performed at age eight among the Brahmins, at age 11 among the Kshatriyas, and age 12 among Vaishyas.[3][18] Apastamba Gryha Sutra, in verse 1.1.1.27, places a maximum age limit of 24 for the Upanayana ceremony and start of formal education. However, Gautama Gryha Sutra and other ancient texts state that there is no age restriction and anyone of any age can undertake Upanayanam when they feel they initiate their formal studies of the Vedas.In some regions, in modern times, boys and girls undergo the tradition of Upanayana initiation when they start their formal schooling.[20] In ancient and medieval eras, texts such as Harita Dharmasutras, Asvalayana Grhya Sutra and Yama smriti suggest women could begin Vedic studies after the Upanayana rite of passage.

Girls who decided to become a student underwent the Upanayana rite of passage, at the age of 8, and thereafter were called Brahmavadini. They wore a thread or upper garment over their left shoulder.[6] Those girls who chose not to go to a gurukul were called Sadyovadhu (literally, one who marries straight). However, the Sadyovadhu, too, underwent a step during the wedding rituals, where she would complete Upanayana, and thereafter wear her upper garment (saree) over her left shoulder.[6] This interim symbolic Upanayana rite of passage for a girl, before her wedding, is described in multiple texts such as the Gobhila Gryha Sutra verse 2.1.19 and some Dharmasutras.The ancient Sanskrit texts offer a diverse view while describing yajñopavītam or upavita. The term upavita was originally meant to be any upper garment, as stated in verse 2.2.4.22–2.2.4.23 of Apastamba Dharmasutra or, if the wearer doesn't want to wear a top, a thread would suffice.[29] The thread identified a person who is studying at a school or has graduated. The ancient Indian scholar Haradatta states, "yajñopavītam means a particular mode of wearing the upper garment, and it is not necessary to have the yajñopavīta at all times".[29] The Gobhila Gryha Sutra similarly states, at verse 1.2.1 in its discussion on Upanayana, that "the student understands the yajnopavita as a cord of threads, or a garment, or a rope of kusa grass", and it is its methods of wearing and the significance that matters.[29] The proper manner of wearing the upper garment or thread, state the ancient texts, is from over the left shoulder and under the right arm.[29]

The idea of wearing the upper garment or sacred thread, and its significance, extended to women.[6] This is reflected in the traditional wearing of sari over the left shoulder, during formal occasions and the celebration of rites of passage such as Hindu weddings. It was also the norm if a girl undertakes the Upanayana ceremony and begins her Vedic studies as a Brahm.