Runes and Sounds in the Viking Age
The "younger" futhork uses only 16 characters to represent several dozen sounds. Thus, each rune represents several different sounds. For example, , the rune for "u" is used for the sounds "u", "o", "y", "au" and "ø". And "i" is used for the sounds "e", "æ", "o", "æi", or "j". And for many of the consonants, the same rune is used both for the voiced and unvoiced form, such as "k" for both "k" and "g".
The younger futhork represents a deliberate reform of the runic alphabet, with a reduction of the number of letters, and a simplification of the forms. The younger futhork emerged sometime before the year 800, and quickly spread throughout the region. It was easier to write and took less room, although it was more difficult to read.
When runic writing was developed early in the 1st millennium, the 24 characters making up the elder futhork corresponded nearly perfectly to the phonemes that made up the old Norse language. One sign represented one sound, and one sound was represented by only one sign.
During the period from 550 to 750, the old Norse language changed rapidly. New sounds were added, resulting in a drift between spoken and written language.
At the end of this period, the futhork was simplified, resulting in the younger futhork, with only 16 signs. These 16 signs had to represent even more sounds than the 24 signs of the elder futhork. With this change, one sign represented many sounds, and one sound could be represented by more than one sign. The simplicity of the original system was lost.