It is similar in appearance to the archaic Greek letter sho (ϸ), although the two are historically unrelated.

However, in modern Icelandic it represents a laminal voiceless alveolar non-sibilant fricative [θ̠],[2][3] similar to th as in the English word thick, or a (usually apical) voiced alveolar non-sibilant fricative [ð̠],[2][3] similar to th as in the English word the.

Modern Icelandic usage generally excludes the latter, which is instead represented with the letter eth ⟨Ð, ð⟩; however, [ð̠] may occur as an allophone of /θ̠/, and written ⟨þ⟩, when it appears in an unstressed pronoun or adverb after a voiced sound.

This was the longest-lived use, though with the arrival of movable type printing, the substitution of ⟨y⟩ for ⟨Þ⟩ became ubiquitous, leading to the common "ye", as in 'Ye Olde Curiositie Shoppe'.

[6] The first printing of the King James Version of the Bible in 1611 used ye for "the" in places such as Job 1:9, John 15:1, and Romans 15:29.

Its pronunciation has not varied much, but before the introduction of the eth character, þ was used to represent the sound [ð], as in the word "verþa", which is now spelt verða (meaning "to become") in modern Icelandic or normalized orthography.