The word rune means secret or mystery. Each rune is a symbol and linked to an esoteric principle. Runes convey the messages of the gods to us humans. But also the other way round. They also transmit messages from humans to the gods. Even to nature.
The oldest rune system is the older Futhark, which consists of 24 characters.
Ancient records tell us that it was used as early as 100 BC, but possibly as early as 200 BC.