What the tradition itself says about runes and what modern rune divination does are separated by a considerable gap, and the gap has identifiable contents.
The mythological charter is strong. In the Havamal, Odin hangs nine nights on the windswept tree, wounded by a spear, given to himself, and takes up the runes screaming, an image of knowledge won through ordeal that has no equivalent in the alphabetic origin stories of other scripts. The Eddas and the sagas contain rune charms: for healing, for childbirth, for cursing, carved and reddened. Bind-runes, characters combined into a single figure, appear on real objects. The magical use is genuine.
Divination is thinner. Tacitus, writing about the Germans around 98 CE, describes cutting a fruit-bearing branch into strips, marking them with signs and casting them on a white cloth, and this is the standard citation for runic divination. It is also the only substantial classical description, it predates the earliest surviving runic inscriptions, and Tacitus says notae, marks, not runes. Nothing in the medieval Norse corpus describes a rune-casting system of the kind now practised.
The modern practice, drawing runes from a bag, laying them in spreads, reading upright and reversed positions, assigning each a divinatory meaning, was assembled in the twentieth century, and the popular English-language form of it dates largely to the 1980s. Reversed meanings in particular are borrowed from tarot practice; several runes are symmetrical and cannot be reversed at all, and the systems handle that inconsistently.
A darker layer also has to be named. The Armanen runes of Guido von List, invented in 1902, are an eighteen-character system with no epigraphic basis, and List's occult nationalism fed directly into the runic symbolism the Nazi state adopted. Modern heathen organisations have publicly repudiated that use, and the symbols remain contested in consequence.