There is some evidence that, in addition to being a writing system, runes historically served purposes of magic. This is the case from the earliest epigraphic evidence of the Roman to the Germanic Iron Age, with non-linguistic inscriptions and the alu word. An erilaz appears to have been a person versed in runes, including their magic applications.

A rune is a letter in a set of related alphabets known as runic alphabets native to the Germanic peoples. Runes were used to write Germanic languages before they adopted the Latin alphabet, and for specialised purposes thereafter. In addition to representing a sound value, runes can be used to represent the concepts after which they are named (ideographs). Scholars refer to instances of the latter as Begriffsrunen. The Scandinavian variants are also known as fuþark, or futhark, these names derived from the first six letters of the script, ⟨ᚠ⟩, ⟨ᚢ⟩, ⟨ᚦ⟩, ⟨ᚨ⟩/⟨ᚬ⟩, ⟨ᚱ⟩, and ⟨ᚲ⟩/⟨ᚴ⟩, corresponding to the Latin letters ⟨f⟩, ⟨u⟩, ⟨þ⟩/⟨th⟩, ⟨a⟩, ⟨r⟩, and ⟨k⟩. The Anglo-Saxon variant is futhorc, or fuþorc, due to changes in Old English of the sounds represented by the fourth letter, ⟨ᚨ⟩/⟨ᚩ⟩.