A miracle is anything unexplainable which seems to defy the laws of physics, nature, or logic in order to achieve an end, usually something very good or mystifying. There have been several proposed definitions of miracles. Some definitions are much looser include anything that causes wonder or amazement, even if it's completely explainable.
Some Christians have a skewed and often disturbing view of what a miracle is. To them, a miracle is something which spares them pain or hardship, even if it deals out said pain or hardship on someone else. For example, a Christian man is driving down the street when a car comes out of nowhere and hits him. Both cars are totalled and everyone dies except him. Later on, when he's interviewed by the local news station he claims that God was watching out for him (Argument from incomplete devastation). Obviously this is total bunk. The Christian God is said to be omnipotent and omniscient, thus he knew the accident would happen, he knew how to save everyone, and he was able to. Why he didn't is anyone's guess. In any case, the fact that one man survived doesn't mean that he owes his continued existence to God. This is also a good example of the problem of evil.
Since 1964, the James Randi foundation offers a cash prize for any demonstration of paranormal phenomena under controlled conditions. Approximately 1000 applicants have attempted to claim the prize  but no claim has been successful so far. The prize money has grown from US$1,000 to $1,000,000 from donations.
There are various definitions for a miracle, with different types of events being included. This tends to create confusion in terminology. For example:
- Rare event: Rare beneficial events that defy explanation by known physical processes.
- "I was walking down the street and an iron girder suspended above a construction site fell as I was walking underneath. Just as it was about to hit me it suddenly flew to the left and landed in the middle of the street, completely missing me and everyone else there! God was watching out for me."
- Fortunate events: Subjectively fortunate occurrences. 
- "My son was just born this morning. He has the most beautiful eyes in the world. Childbirth is such a miracle!"
- Divine act: Rare events that are believed to be caused by God.
- "Then Moses stretched out his hand over the sea; and the Lord caused the sea to go back by a strong east wind all that night, and made the sea into dry land, and the waters were divided. (Exodus 14:21)"
These are not usually used to argue for the existence of God because it would be begging the question.
- David Hume: A miracle is a violation of the laws of nature [...] a firm and unalterable experience has established these laws. 
This is a very influential definition given in Of Miracles. It is not without controversy because if natural laws are that which occurs in experience, miracles arguably cannot happen.
- Indicative: A miracle is an event whose only adequate explanation is the extraordinary and direct intervention of God. 
This definition is problematic because there are many unexplained phenomena which might one day be explaned (e.g. dark matter). How are we to distinguish between unknown natural phenomena and acts of God? This is walking into the arms of God of the gaps and the argument from ignorance.
- Informational: Scientific knowledge and numerical codes are considered miracles by some Muslim apologists.
- "Another mathematical miracle of the Qur'an is the manner in which the number 19 is numerologically encoded in verses. "
Fortunate events as miracles
- Main Article: Argument from fortunate events
In his book, Unweaving the Rainbow, Richard Dawkins coined a term to deal with "miracles" that merely turn out to be coincidental in nature: PETWHAC, or "Population of Events That Would Have Appeared Coincidental". Dawkins points out that many mundane events occur every single day to every person on the planet, and the human mind has a great capacity to identify patterns where none exist. Dawkins explains that there is a space of events with perfectly normal probability, which could be interpreted as "miraculous" by people who have that sort of mindset.
For instance, suppose that you are thinking about a friend, and that friend just happens to call you. Is this event supernatural in nature? Extremely doubtful. People think about others all the time, and they also call each other all the time. Given enough time, there is a virtual guarantee that a coincidence of this nature will occur.
Another interesting point to think of is what if someone is out for a jog one day and suddenly drops dead right then and there, should that also be considered a "miracle"? Arbitrarily defining miracle as something beneficial that makes one feel good does nothing to support the case of miracles. The difference is when something terrible happens - people try to find a rational explanation for said occurrence. When they cannot find an explanation (typically due to lack of technology to do so) they simply say, "Oh, that's a tragedy.." Yet why do they not consider this event a miracle?
Calling something unexpected and unexplained a "miracle" is merely wishful thinking and rather misleading.
The alleged resurrection of Jesus plays a major role in some varieties of Christian apologetics. The reasons to doubt such claims are many, including the common sense observation that most people would be skeptical of miracles outside their religion, the importance of observed regularities in historical research, and empirical considerations such as the lack of modern miracles.
Gautama Buddha is recorded as performing many miracles.
In Islam, miracles are claimed based on the properties and inerrancy of the Qur'an.
- Main Article: Miracles in history
Miracles are recorded in secular sources throughout history and in many different religions.
Near-death and temporary clinical death
A person being near death or even clinically dead for 5, 10, or even 30 minutes and then coming back is not evidence of a miracle in the strict/technical sense. There is a phenomenon called "autoresuscitation" (AR) that is easily understood in terms of known human physiology that is accepted by the medical community. Reports of "autoresuscitation" (Google it, it is not too difficult to find medical journal articles on the topic) after less than 15 minutes of clinical death are not even almost astounding, and there have been cases of AR after 33 or 37 minutes documented. If cases of hypothermia can be included, this period can be extended to over 45 minutes to 1 hour. This is largely because hypoxic brain damage is suppressed at lower temperatures.
Perhaps counter-intuitively, according to the modern understanding of medicine it would be far more miraculous for an amputee to regrow an entire arm or leg than it would be for someone to clinically die for (say) 19 minutes and then wake back up.
- Main Article: Faith healing
In modern times, many Christian evangelists have claimed the ability to supernaturally heal diseases. Some Christians have cited them as powerful evidence for the existence of God and the truth of Christianity. However, investigations of faith healers by men such as medical doctor William Nolen and magician James Randi have failed to find any evidence of actual miracles, and have turned up much evidence of fraud or, at best, self-deception. God apparently does not miraculously replace missing limbs and there is no coherent reason why this is the case.
- Argument from miracle testimony
- Argument from biblical miracles
- Argument from observed miracles
- Argument from fortunate events
Miracles, Stanford Encyclopedia of Philosophy