A prophet usually refers to a person who has the ability to do either of two things. He could get a direct message from God or a Divine Being, with the message supposed to be shared to other people; or he can be a person who can somehow tap into a some kind of deep, hidden knowledge and be able to make predictions about the future, which is either of certain individuals or of world events.
The definition of a prophet as making predictions of future events is also known as a psychic or a seer. For people who do not believe in the Divine, a prophet will likely be seen as a person who falsely believes that God is talking to him. Even the believers of many religions distinguish between true and false prophets.
Based on the Judeo-Christian-Islamic traditions, prophecies were once thought to be more common. In fact, the three religions also shared prophets – Noah, Abraham, and Moses. Jesus was also considered a prophet, a belief shared by both Christians and Muslims. But the Muslims further believe that Muhammad is the final prophet who has spoken about how God should be venerated.
Most recently, some people are also being considered as prophets with a link to God. For example, Joseph Smith, the founder of the Church of Jesus Christ of Latter Day Saints (more popularly known as the Mormons) is considered a prophet by his followers. Seventh Day Adventists, on the other hand, believe that the co-founder of their church Ellen White is also a prophet.