Sanskar
Upanayana
The sacred thread and the step toward a teacher — in families that keep it.
When
By shakha and family. Not a rite of every community.
Upanayana belongs to families whose shakha gives the yajnopavita, the sacred thread. It is an initiation into study and restraint, and a memory of three debts: to the sages, the ancestors, and the devas. Forcing it on every Indian is not tradition.
Where it is performed, begging alms, the girdle, and the Gayatri may be part of the day. Confirm age and form with your own acharya. Houses that do not keep it shape a life through other sanskars, such as vidyarambha and vivaha.
This is a general introduction. Sequence, materials, and timing change with family, region, and shakha. Your priest and your own custom have the last word.