For such a simple word, a lot went into the development of the second person pronoun you. Originally, it was only used as a dative and accusative plural, with thou being the singular version and ye being the nominative, but you began to be used as a term of respect and eventually became more and more common until thou died out entirely. You has been around in some form for as long as English has: it's been attested as iow, eow, geau, ȝeu, yhw, æu, ȝow, and yewe until the modern spelling was widely accepted as correct in the late sixteenth century. This form of the word is thought to have been influenced by the different declensions of ye and the German word euch, meaning "to you". You has been increasing in literary usage since the 1960s and now constitutes about 0.3% of all English words.
Hello! I'm Adam Aleksic. This year, I graduated from Harvard University with a degree in Government and Linguistics. There, I co-founded the Harvard Undergraduate Linguistics Society and wrote a thesis on Serbo-Croatian language policy, magna cum laude. In addition to etymology, I also really enjoy philosophy, trivia, vexillology, geography, board games, conlanging, art history, and law.