Sacred Thread in Hindu called as Raksha. It is tied by a priest or an older family member, typically grandparents or parents on the wrists of all the people attending the prayer ceremony.
According to Bhagavad Gita, no one on Earth is free from three Guṇas (tendencies, qualities, attributes) of nature: Rajas (passion), Tamas (darkness or destruction) and Satva (purity). These gunas deeply affect our state of mind, our moods, nature and our behavior. For example, : A mother who feeds her baby is said to be Satvik; She plays and adores her baby as Rajas and gives her naps generously as Tamas. The thread on the wrist helps one control mood swings that one experiences time and again in their daily life and gets them into the Satvik state, which is pure and placid.
The three nadis of ida, pingala and sushumna affect the vata, kapha and pitha components of the body. It is believed the sacred thread variously known as nadachadi, mouli, chandramouli or kalava, has qualities that are beneficial to keep the nadis in balance. During puja ceremonies, the thread is tied after the recitation of certain mantras bestowing it with energy. The thread is mainly red in color but is sometimes mixed with yellow and some other colors. The color red is a beneficial one and represents energy and strength. It has the capacity to improve health.
Yellow Thread is associated with joy, happiness and energy. It is usually used in marriages.White Thread means safety, purity, and cleanliness. White sacred threads are used for “Yajnopavita, Janeau or Poonal”.Black Thread is a mysterious color associated with fear and the unknown. Black thread is worn as a protection from evil eyes.
The thread also represents the Gods of the Hindu trinity: Brahma, Vishnu and Mahesh as well as their spouses; Saraswati, Lakshmi and Parvati. The red thread also substitutes as a form of clothing during a puja and is also tied around items of worship during puja ceremonies. It represents the blessings of God.