God is like the Hound of Heaven, according to Francis Thompson’s famous poem. He pursues us to the last moment, begging for entrance into our hardened hearts, so that He may pull us to Himself and save us. He sent His Son, but the world did not accept Him, killing Him instead. On the Cross Christ draws to His pierced Heart all those who are willing. But for those who still refuse Him down the ages, He sends another means of reaching us, namely the Virgin Mary, lifting the veil to eternity so that she may speak to us directly through apparitions, asking us to heed His voice.
The vast number of her appearances over the centuries shows her love for us. Some scholars have counted about 2,500 Marian apparitions over the past 2000 years though the Church has only officially recognized a few. Each apparition has its own charism, but all authentic ones – whether fully investigated by the Church or not - have in common that they call for conversion, repentance, prayer, and love of God. Many have miracles to show: healings of various illnesses, miraculous manifestations of various kinds. But the greatest miracles are the conversions, for no stone, indeed no metal, is as tough as a hardened heart.
Jesus is the doctor of our souls who knows how to find an entrance point, if any. And Mary is His most powerful and yet gentle means to gain entry. Her compassion and love for us is greater than that of the best mother on earth. Those who might tremble in front of the justice of God and (wrongly) despair of finding mercy in Him, often feel more comfortable turning to the blessed Virgin.
Jesus told us the parable of the Prodigal Son to show the immense love of God. When the profligate son finally decides to return, the Father is already looking out for Him, then runs towards Him and treats Him like the apple of His eye. If one were to add the blessed Mother to the parable, one would say that the Father sends her to his sinful son while he is starving among the pigs, reminding him of his Father’s plenty and giving him the assurance that he will be accepted back into the fold. In the parable, the young man hopes to be accepted merely as a servant. If the Virgin Mary had been there, she would have shown him that he would be welcomed back as the much-beloved son.
Let us listen to the voice of Mary who always calls us back to God.
The section first proposes a definition of apparitions, then lists the main Marian apparitions as well as giving the criteria which the Church uses to discern their authenticity. Then it is shown how the Virgin Mary intervenes in different countries, adapting to different audiences, and how she serves for the Church. The section ends with a study of how we should respond to such calls, namely through faith, prayer, penance, concern for peace and unity, and by accepting her as our Mother.
 http://www.miraclehunter.com/marian_apparitions/index.html. And here’s a map of those apparitions: aleteia.org/2019/05/15/this-map-illustrates-500-years-of-marys-apparitions/