The Runic alphabets are a set of related alphabets using letters known as runes, formerly used to write Germanic languages, mainly in Scandinavia and the British Isles, but before Christianization also on the European Continent. The Scandinavian variants are also known as Futhark (or fuþark, derived from their first six letters: F, U, Þ, A, R, and K); the Anglo-Saxon variant as Futhorc (due to sound changes undergone in Old English by the same six letters).

The runes were introduced to, or invented by, the Germanic peoples in the 1st or 2nd century (The oldest known runic inscription dates to ca. the 160s and is found on a comb discovered in the bog of Vimose, Funen. The inscription reads harja). While at this time the Germanic language was certainly not at the Proto-Germanic stage any longer, it may still have been a continuum of dialects not yet clearly separated into the three branches of later centuries, viz. North Germanic, West Germanic and East Germanic. Most of the early runes from the Scandinavian countries are assumed to be in the Proto-Norse, the common ancestor language of the modern North Germanic languages. No distinction is made in surviving runic inscriptions between long and short vowels, although such a distinction was certainly present phonologically in the spoken languages of the time. Similarly, there are no signs for labiovelars in the Elder Futhark (such signs were introduced in both the Anglo-Saxon Futhorc and the Gothic alphabet as variants of p; see peorð.)

As Proto-Germanic evolved into its later language groups, the words assigned to the runes and the sounds represented by the runes themselves began to diverge somewhat, and each culture would either create new runes, rename or rearrange its rune names slightly, or even stop using obsolete runes completely, to accommodate these changes. Thus, the Anglo-Saxon Futhorc has several runes peculiar unto itself to represent diphthongs unique to (or at least prevalent in) the Anglo-Saxon dialect.

However, the fact that the younger Futhark has sixteen runes, while the Elder Futhark has twenty four, is not fully explained by the some six hundred years of sound changes that had occurred in the North Germanic language group. The development here might seem rather astonishing, since the younger form of the alphabet came to use fewer different rune-signs at the same time as the development of the language led to a greater number of different phonemes than what had been present at the time of the older futhark.

For example, voiced and unvoiced consonants merged in script, and so did many vowels, while the number of vowels in the spoken language increased. From about 1100, this disadvantage was eliminated in the medieval runes, which again increased the number of different signs to correspond with the number of phonemes in the language. The name given to the signs, contrasting them with Latin or Greek letters, is attested on a 6th century alamannic runestaff as runa, and possibly as runo on the Einang stone (ca. 4th century). The name is from a root run- (Gothic runa) meaning "secret" (c.f. also the chapters of the Kalevala, called runo, plural runot, a loan from North Germanic). The earliest runic inscriptions were certainly not coherent texts of any length, but simple markings on artifacts (e.g. bracteates, combs, etc.), giving the name of either the craftsman or the proprietor, or, sometimes, remaining a linguistic mystery. Because of this, it is possible that the early runes were not so much used as a simple writing system, but rather as magical signs to be used for charms, or for divination. The name rune itself, taken to mean "secret, something hidden", seems to indicate that knowledge of the runes was originally considered esoteric, or restricted to an elite. The eerie 6th century Björketorp Runestone warns in Proto-Norse using the word rune in both senses: Haidz runo runu, falh’k hedra ginnarunaz. Argiu hermalausz, ... weladauþe, saz þat brytz. Uþarba spa. Here, I have hidden the secret of powerful runes, strong runes. The one who breaks this memorial will be eternally tormented by anger. Treacherous death will hit him. I foresee perdition.

The same curse and use of the word rune is also found on the Stentoften Runestone. There are also some inscriptions suggesting a medieval belief in the magical significance of runes, such as the Franks Casket (AD 700) panel. However, it has proven difficult to find unambiguous traces of runic "oracles": Although Norse literature is full of references to runes; it nowhere contains specific instructions on divination or magic. There are at least three sources on divination with rather vague descriptions that may or may not refer to runes, Tacitus’ Germania, Snorri Sturluson’s Ynglinga saga and Rimbert’s Vita Ansgari. The first source, Tacitus’ Germania, describes "signs" chosen in groups of three. A second source is the Ynglinga saga, where Granmar, the king of Södermanland, goes to Uppsala for the blót. There, the chips fell in a way that said that he would not live long (Féll honum þá svo spánn sem hann mundi eigi lengi lifa). The third source is Rimbert’s Vita Ansgari, where there are three accounts of what seems to be the use of runes for divination, but Rimbert calls it "drawing lots." One of these accounts is the description of how a renegade Swedish king Anund Uppsale first brings a Danish fleet to Birka, but then changes his mind and asks the Danes to "draw lots." According to the story, this "drawing of lots" was quite informative, telling them that attacking Birka would bring bad luck and that they should attack a Slavic town instead.

Some later runic finds are on monuments (rune stones), which often contain solemn inscriptions about people who died or performed great deeds. For a long time it was assumed that this kind of grand inscription was the primary use of runes, and that their use was associated with a certain societal class of rune-carvers. However, in the middle of the 1950s, about 600 inscriptions known as the Bryggen inscriptions were found in Bergen. These inscriptions were made on wood and bone, often in the shape of sticks of various sizes, and contained inscriptions of an everyday nature - ranging from name tags, prayers (often in Latin), personal messages, business letters, expressions of affection, to bawdy phrases of a profane and sometimes even vulgar nature. Following this find, it is nowadays commonly assumed that at least in late use, Runic was a widespread and common writing system. In a treatise called de inventione litterarum, preserved in 8th and 9th century manuscripts, mainly from the southern part of the Carolingian Empire (Alemannia, Bavaria), ascribed to Hrabanus Maurus, a runic alphabet consisting of a curious mixture of Elder Futhark with Anglo-Saxon Futhorc is recorded. The alphabet is traditionally called "Marcomannic runes," but it has no connection with the Marcomanni and is rather an attempt of Carolingian scholars to represent all letters of the Latin alphabets with runic equivalents

The runes are a major element in Germanic neopaganism, often used to indicate ancestry, aesthetically in crafts and for ritual purposes. New age and Wiccans may sometimes also sometimes use runes under various conditions, such as divination.

Historical and fictional runes appear commonly in modern popular culture, particularly in fantasy literature, video games and various other forms of media.