Mangalsutra is the combination of two words ‘Mangal’ and ‘Sutra.’ Mangal means that which is auspicious and sutra here refers to Mala or chain. Mangalsutra is the most important symbol of a Hindu married woman.
Mangalsutra is made using yellow thread and black pearls. The yellow thread is associated with Brihaspati Navagraha and it symbolizes auspiciousness. The black pearl helps in absorbing all forms of negative energy.
A strong Brihaspati is necessary for a happy married life.
Another belief is that Yellow thread represents Goddess Parvati and the black pearls represent Shiva. The belief is that Shiva protects the husband and Goddess Parvati bless the married woman with healthy children, peace and prosperity.
The other beliefs are that a woman wears Mangalsutra for the long life of her husband. It protects her husband from all dangers.
Mangalsutra is like a kavach (shield) it protects her from all forms of danger.
Yellow thread is today replaced with gold.