The Icelandic orthography uses a Latin-script alphabet including some letters duplicated with acute accents; in addition, it includes the letter eth, transliterated as ⟨d⟩, and the runic letter thorn, transliterated as ⟨th⟩ ; ⟨æ⟩ and ⟨ö⟩ are considered letters in their own right and not a ligature or diacritical version of their respective letters. Icelanders call the ten extra letters, especially thorn and eth, séríslenskur, although they are not. Eth is also used in Faroese and Elfdalian, and while thorn is no longer used in any other living language, it was used in many historical languages, including Old English. Icelandic words never start with ⟨ð⟩, which means the capital version ⟨Ð⟩ is mainly just used when words are spelled using all capitals.

The acute accent, ◌́, is a diacritic used in many modern written languages with alphabets based on the Latin, Cyrillic, and Greek scripts. For the most commonly encountered uses of the accent in the Latin and Greek alphabets, precomposed characters are available.