"What falls but never breaks and what breaks but never falls?" is a riddle, and the answer is "night and day," because "night" falls and "day" breaks. The riddle is meant to puzzle the reader.
Most riddles are made to mystify or confuse the reader, forcing them to think of an answer that may be totally logical but still very difficult to figure out. There are many examples of riddles that can be found on the Web. Another example of a riddle is, "What is an English word that refers to the burning of wood once the first letter is taken off?" The answer to this riddle would be the word "member" because when the first letter is taken off, the word becomes "ember."
Other riddles can ask a question from the point of view of the answer. "Feed me and I live, but give me a drink and I die. What am I?" is an example of such a riddle. The reader must then try to figure out what the answer is based on from this personified question. The answer to this riddle, of course, is fire. When "fed" combustible materials, fire will continue to burn, but when doused with water, the "drink," it will be extinguished. Many riddles are written in this manner.