Analysis of information sources in references of the Wikipedia article "Marian apparition" in English language version.
Even if the Church recognizes an apparition as worthy of belief, no Catholic is obligated to believe in any private revelation, such as an apparition. The Church simply says that a person can find spiritual aid from an apparition, if he or she so chooses.
An apparition is best understood as a specific kind of vision in which a person or being not normally within the visionary's perceptual range appears to that person, not in a world apart as in a dream, and not as a modification of a concrete object as in the case of a weeping icon or moving statue, but as part of the environment, without apparent connection to verifiable visual stimuli.