Shin (letter) languages, as follows: In the Arabic alphabet, ' is at the original (21st) position in Abjadi order. A letter variant ' takes the place of Samekh at 15th position. "" represents , and is the 13th letter of the modern alphabet order and is written thus: The Arabic letter "šīn" was an acronym for "something" ( "šayʾ(un)" ) meaning the unknown in algebraic equations. In the transcription into Spanish, the Greek letter "chi" (χ) was used which was later transcribed into Latin "x". According to some sources, this is the origin of "x" used for the unknown in the equations.
Letter (alphabet) and order of appearance correspond closely. The Greek alphabet, adapted around 800 BCE, added four letters. This was the first alphabet assigning letters not only to consonant sounds, but also to vowels. The Roman Empire brought the development and refinement of our Roman alphabet, beginning around 500 BCE. The Romans added or dropped certain letters to accommodate Greek and Etruscan words; they also experimented with styles such as cursive when writing in ink. By about the fifth century CE, the beginnings of lowercase letterforms began to emerge in Roman writing, but they did not come into common use until the