The Hail Mary is a traditional Catholic prayer that asks for the intercession of the Blessed Virgin Mary. It is also called Angelic Salutation and is comprised of three parts, addressed to Mama Mary.
The first part is taken from the words of the archangel Gabriel (Luke 1:28). The second part, the words of St. Elizabeth, the mother of St. John the Baptist, was dded to the first part by about 1000 CE. Meanwhile, the closing petition came into general use during the 14th and 15th century. It received its official formulation in 1568. (Read: Thousands of Children Participate In “One Million Children Praying The Rosary” 2021)
Aside from the prayer being recited in the Rosary and the Angelus prayers, it is also often assigned as penance during the sacrament of reconciliation. Here is the prayer.