‘Well, it is a simple knotted black thread. Kashi is protected by Bhairavnath, who is a great and loyal servant of Lord Shiva. If you go to Kashi and don’t see the Kaal Bhairav temple, your yatra or journey is considered incomplete. You will get a Kashi thread from there, which you have to wear for Bhairavnath to protect you. Since the Kashi trip is difficult, he will accompany you in his invisible form until you reach home safely.
