For as long as time can tell humanity has always tried to interpret dreams. In the bible there are scriptures that speak of dreams and visions. The story of Joseph the dreamer is an example of people who interpret dreams. There were men in charge of interpreting dreams they were know as wise men.
My grand mother believes that her dreams have a meaning and a way of telling her certain things. If she saw someone in her dreams: that could possibly mean that good fortune will soon come or some unfortunate event will happen to them.
Psychologists say that dreams signal-repressed memories. Florence false interpretation study shows that psychologists can make people recall events that never happened due to false dream interpretation. (Dream Lecture)
There are many websites and books that are designed to provide glossaries for meaning of certain things. Dreammoods.com