What was the name of the 16-character runic alphabet used across much of the Viking Age?

The 16-character runic alphabet used across much of the Viking Age was Younger Futhark.

Younger Futhark developed from Elder Futhark during the late eighth century. Although the older system had 24 signs, the Viking-era alphabet reduced that number to 16. This meant that one rune could represent several related sounds, so readers relied heavily on context.

The alphabet appears in two principal forms: long-branch runes, often associated with monuments and formal inscriptions, and short-twig runes, which were convenient for everyday carving. Staveless runes later developed in parts of Scandinavia, especially Sweden.

The name “Futhark” comes from the first six rune names: f, u, þ, a, r and k. Younger Futhark should not be confused with Anglo-Saxon futhorc, which expanded the alphabet to represent sounds used in Old English.