Rākhī derives from the Sanskrit rakṣikā, a join: rakṣā protection.
On this day, sisters of all ages tie a talisman, or amulet, called the rakhi, around the wrists of their brothers, symbolically protecting them, receiving a gift in return, and traditionally investing the brothers with a share of the responsibility of their potential care.
Read more about this unique festival here: https://www.rohitghai.com/rakshabandhan-रक्षाबंधन/