The reduction, somewhat paradoxically, happened at the same time as phonetic changes led to a greater number of different phonemes in the spoken language, when Proto-Norse evolved into Old Norse. Thus, the language included distinct sounds and minimal pairs which were not separate in writing, the Younger Futhark is divided into long-branch and short-twig runes, in the 10th century further expanded by the Hälsinge Runes or staveless runes. The lifetime of the Younger Futhark corresponds roughly to the Viking Age, usage of the Younger Futhark is found in Scandinavia and Viking Age settlements abroad, probably in use from the 9th century onward. During a phase from about 650 to 800, some inscriptions mixed the use of Elder and Younger Futhark runes, by the late 8th century, the reduction from 24 to 16 runes was complete. The main change was that the difference between voiced and unvoiced consonants was no longer expressed in writing, other changes are the consequence of sound changes that separate Old Norse from Proto-Norse and Common Germanic. The first ætt was reduced to its first six letters, fuþąrk, the second ætt lost the æ and p runes. The j rune was rendered due to Old Norse sound changes. The old z rune was kept but moved to the end of the row in the only change of letter ordering in Younger Futhark. The third ætt was reduced to four runes, losing the e, ŋ, o and d runes, the names of the 16 runes of the Younger futhark are recorded in the Icelandic and Norwegian rune poems. The exceptions to this are, yr which continues the name of the unrelated Eihwaz rune, thurs and kaun, in cases the Old Norse, Anglo-Saxon. The Younger Futhark is divided into long-branch and short-twig runes, the difference between the two versions has been a matter of controversy. Later other runic inscriptions with the runes were found in other parts of Sweden. They were used between the 10th and 12th centuries, the runes seem to be a simplification of the Swedish-Norwegian runes and lack certain strokes, hence the name staveless. They cover the set of staves as the other Younger Futhark alphabets. This variant has no assigned Unicode range, in the Middle Ages, the Younger Futhark in Scandinavia was expanded, so that it once more contained one sign for each phoneme of the old Norse language. Inscriptions in medieval Scandinavian runes show a number of variant rune-forms. Medieval runes were in use until the 15th century, of the total number of Norwegian runic inscriptions preserved today, most are medieval runes. Notably, more than 600 inscriptions using these runes have been discovered in Bergen since the 1950s and this indicates that runes were in common use side by side with the Latin alphabet for several centuries
The ogam lochlannach, Book of Ballymote, fol. 170v
The Younger Futhark: Danish long-branch runes and Swedish/Norwegian short-twig runes.