Marian apparitions are reported supernatural appearances of the Blessed Virgin Mary to one or more persons on earth. The Church investigates claimed apparitions through a rigorous process and may declare them 'worthy of belief,' meaning the faithful may choose to believe them but are not required to. Major Church-approved apparitions include: Our Lady of Guadalupe (Mexico, 1531), where Mary appeared to St. Juan Diego and left her image on his tilma; Our Lady of Lourdes (France, 1858), where Mary appeared to St. Bernadette Soubirous and a healing spring emerged; Our Lady of Fatima (Portugal, 1917), where Mary appeared to three shepherd children and gave three secrets about the future. Other approved apparitions include Our Lady of the Miraculous Medal (Paris, 1830), Our Lady of La Salette (France, 1846), and Our Lady of Knock (Ireland, 1879). Apparitions are considered private revelation — they cannot add to or contradict the deposit of faith (public revelation) that closed with the death of the last apostle.