Mu'jiza (Arabic: معجزة, miracle) is an extraordinary act that prophets do against the ordinary natural events, in order to prove their truth. The aim of Mu'jiza is to prove their divine appointment.
There are some signs mentioned for Mu'jiza, some of them are: challenging and not being defeated. According to Shi'a theologians, Mu'jiza does not defy the rule of causality. According to the rule of causality, every effect is related to a cause, so the question is how there could happen something extraordinary, and what are the causes to this events? The answer is that although an event could not happen without a cause, this cause could be unknown to us. The range of the human science is limited to experiments and natural causes, and this cannot include supernatural causes. So there are supernatural causes for the extraordinary events which is only available to people chosen by God.
There are many Mu'jizas reported from the prophets, some of which are sensual and could be perceived by sense, and others are intellectual and could only be perceived by intellect. Some of the most famous Mu'jizas of prophets are: the cooling of fire, the stick converting into a serpent, reviving the dead, and Qur'an.
Although all of Mu'jizas were extraordinary, the Mu'jizas of the prophets covers a variety of occurrences; this differences is because of the differences of the knowledge and science of the people, so the divine wisdom requires that the Mu'jiza of every prophet being appropriate to the people they are sent to, so the Mu'jiza is like what they have skill in and know so people do not have argument against God. In the time of Musa (a) [Moses] doing magic was prevalent and magicians knew the magic form non-magic, God made Mu'jiza of Musa (a) the stick converting into a serpent, and defeat the magicians and they acknowledge it being Mu'jiza. In the time of 'Isa (a) [Jesus] the medicine was thriving, so the Mu'jiza of 'Isa (a) was reviving the dead and healing the blind and the deaf, so his superiority over other physicians becomes obvious and this becomes a reason for his truth.