Runes are the principal writting system in Scandinavia.
Runic inscriptions appeared first in Denmark in the first centuries AD. Probably they where inspired by the latin alphabet, but took on their own significanse among Germanic peoples. Like the latin alphabet is called "alphabet" due to the first letters being alpha (A) and beta (B), a runic alphabet is called a "futhark" because listings of all the runes always begins with the letter "f", "u", "th", "a", "r" and "k". There are several futharks due to the changes in languages among Germanic peoples. The original "elder futhark" developed into an "anglo-saxon furthark" and the "younger futhark", the later for old Norse and was the one that was mostly used by the vikings. The "elder futhark" was phased out during the 8th century. Althrough the latin alphabet eventually won out the futhark, there was a living tradition of runes in remote areas of Scandinavia which continued into the 19th century. Runes where used for everything from marks of a craftsman, to write memory stones, simple messages and magic.
Why and when runes started to considered to have magic ability is still not known. Neighter it's known why the futhark was first invented, but Norse Mythology paints an esotheric story. According to legend, Odin hung on the worldtree Yggdrasil for nine nights without food or drink. Staring into the void beneath the tree and pulled up the runes. It was belived that runes had great magic within them and by carving, naming and painting the runes correctly that magic could be invoked. Victory in battle, love, protections of the gods and the curing of disease could be achived from runic magic. Odin even tells of how he can raise the dead with his runic knowlage.