Runes are the anceint Norse alaphabet. They were used for recording information. They are also used for divination purposes. Each rune has a specific meaning, the meanings of all the runes in a 'throw' tells you the answer to your question.
The most common set of runes used is the Elder Futhark. It contains, I believe, 24 runes. There is no blank rune.
Runes are symbols not just Norse, but that is the most common form. They are ancient symbols equal to letters of the alphabet or pictographs. The traditional Norse ruins are easily researchable and should be treated with a great deal of respect. Each rune means something different. when carved on stone or wood they can be used for divination, but they can be used for spells as well such as carving a candle with a rune to enhance a spell, but make sure you use the right runes with the right spells.