Litany is the same as prayer. From the first centuries the Church used to celebrate prayers preceded by a procession. It is very old the one from April 25, when the feast of St. Mark was not yet celebrated. It was probably instituted in Rome to uproot a pagan festival. Later it was ordered to implore God to deliver us from temporary evils, and cast his blessing on the harvests. They are called major to distinguish them from the lesser, or less solemn, which are celebrated three days before the Ascension.
V/. Blessed Virgin Mary
R/. Pray for us.