“Ex-voto is a spanish word meaning votive offering. In Mexico, an exvoto is most commonly a personal thank you note to God, often taking the form of folk art. In most cases, the exvoto is signed and dated, and explains why the giver is giving thanks - what God did for him or her. In many cases, they tell a very touching personal story. The personal story is what makes them so fascinating. The exvoto is most often left at a church altar. They are very public, yet very personal, professions of faith in God and thanks for favors received.
The most common reason for thanks is health, with many exvotos dedicated after operations. Survival of accidents is a close second. But almost any subject is sufficient to justify creating one, from finding a missing child or pig, to repairing an old car. They were most often commissioned to a local artist since often the person giving thanks was unable to read or write.”
we saw quite alot of these at the FridaKahlo museum in MexicoCity when we were there.
it also seems that ex-voto refers to the little medallions and charms in the shapes of body parts found in cathedrals.