Dhoti (preferably of red or white colour), uttariya and topi are the traditional dress for the janeu or Upanayana ceremony. Such unstitched garments are considered auspicious and pure and therefore used in religious ceremonies even in present times.
In Hinduism, Upanayana is the initiation ritual by which initiates are invested with a sacred thread to symbolize the transference of spiritual knowledge. The sacred thread (Sanskrit: yajnopavitam or Upavita) is a thin sacred cord, composed of distinct cotton strands, worn to symbolize the permission given to the wearer to perform sandhyavandanam and recite the Gayatri mantra. Threads are entwined into strong cords, binding the wearer to tradition and sacred vows.