From World Book:
Miracle is an event that cannot be explained through the known laws of nature. Miracles are generally associated with religion, but any occurrence can be called a miracle if it has no natural explanation.
The major figures in a religion are often credited with performing miracles. These figures include Jesus Christ in Christianity, Moses and the prophets in Judaism, Muhammad in Islam, and various gods in Hinduism. Many religions also teach that lesser holy figures, such as saints and rabbis, may also perform miracles. People may make pilgrimages to certain sacred places and objects to ask for a miracle. For example, Roman Catholic pilgrims travel to the shrine at Lourdes, France. There they pray to the Virgin Mary to plead with God on their behalf for miraculous cures.
Devout members of a religion believe in miracles and consider them a divine sign. Others have an equally firm belief that there is no such thing as a true miracle. They feel that all so-called miracles can be explained through scientific or psychological knowledge.