A prophecy is a claim of what the future will be like, which is not based on any ordinary source of information. In some ways, prophecies are similar to religion. Not all people believe in prophecy. People that do think they come from God or a god. They are often hard to understand and need interpretation. Very often, they concern one very specific event. People who make prophecies are called prophets. In Ancient Greece, people who made prophecies were called oracles, most notably the Oracle of Delphi. Since then, people like Nostradamus have made prophecies.
There are many prophecies in the Bible. Some of these warn of punishments to come. There are two kinds of Bible prophecies. Some are conditional, that is, they include the possibility that the punishment can be avoided based on the hearers changing their ways. An example of this is found in the Book of Daniel. Other prophecies are unconditional. That means that the event will happen no matter what the hearers do to avoid it. There are also Bible prophecies that tell of future blessings. Blessings are good things that happen because of God's mercy and forgiveness. Some prophecies contain both punishment and blessings. Jesus made prophecies like this, warning people to believe in Him and live right, to get the blessing instead of the punishment. While some of the prophecies in the bible about future events are hard to understand, the moral warnings from Jesus are not hard to understand. For this reason, some preachers, like Moses, Jesus and other religious leaders who tell people to live a good life are called prophets by their followers even though they may not tell about future events. Muslims consider Muhammad to be a prophet. Even some modern religious leaders have been called prophets by their followers, such as Joseph Smith, Jr., Dr. Martin Luther King Jr., and Rev. Billy Graham.