By or BY may refer to:
The Byzantine Empire, also referred to as the Eastern Roman Empire and Byzantium, was the continuation of the Roman Empire in its eastern provinces during Late Antiquity and the Middle Ages, when its capital city was Constantinople (modern-day Istanbul, which had been founded as Byzantium).
The bystander effect, or bystander apathy, is a social psychological phenomenon in which individuals are less likely to offer help to a victim when other people are present.
The Byelorussian Soviet Socialist Republic (BSSR, or Byelorussian SSR; Belarusian: Беларуская Савецкая Сацыялiстычная Рэспубліка, translit.
The Byzantine Rite, also known as the Greek Rite or Constantinopolitan Rite, is the liturgical rite used by the Eastern Orthodox Church as well as by certain Eastern Catholic Churches; also, parts of it are employed by, as detailed below, other denominations.
Bydgoszcz (Polish: [ˈbɨdɡɔʂt͡ʂ] ( listen); German: Bromberg [ˈbʁɔmbɛɐ̯k]; Latin: Bydgostia) is a city in northern Poland, on the Brda and Vistula rivers.
BYD Auto Co., Ltd. is a Chinese automobile manufacturer based in Xi'an, Shaanxi Province, and a wholly owned subsidiary of BYD Company.
Bye Bye Birdie is a stage musical with a book by Michael Stewart, lyrics by Lee Adams and music by Charles Strouse.
The Byzantine–Sasanian War of 602–628 was the final and most devastating of the series of wars fought between the Byzantine (Eastern Roman) Empire and the Sasanian Empire of Iran.