Markandeya says:
Oh Lord Brahma! Please teach me that which is secret to the whole world, that which is great, that which gives complete protection, and that which has not been told to anyone.
Brahma says:
Markandeya,There is a great secret Devi Kavacha (Armour of Goddess), which is useful to all human beings and it has not been told to any one.

Kavach is a Sanskrit word which means Armour.
Devi Kavach is a collection of special 61 shlokas from the Markandey Purana and is part of the Durga Saptashti. This Kavacham (armour) protects the devotee in all parts of his body, in all places and in all difficulties. Every part of the body is mentioned and Devi, in all different forms, is being invoked for protection. Further the Goddess in various names and forms is glorified for happiness, wealth, health, power and prosperity.

He who daily reads this Armour of the Goddess, which is even difficult for devas to obtain, in dawn, noon and dusk with devotion would live for one hundred years without getting defeated in all the three worlds with no untimely death in his family. This would destroy all the negativities in life. He will have the glitter of divine power and his fame will increase in this materialistic world.

Here is the most precious chant –