KOI8-RU

KOI8-RU (Кодировка Обмена Информацией, 8 бит, Российская) is an 8-bit character encoding designed for the Russian language. It is based on the KOI8-R encoding, which was itself designed to support the Russian language on Unix-like systems. KOI8-RU extends KOI8-R to include the Ukrainian and Belarusian languages, adding a few additional characters to cover their alphabets.

KOI8-RU is historically significant as one of the earlier widespread encodings for representing Cyrillic script digitally, particularly on Unix platforms. Its design cleverly utilized the unused upper half of the ASCII character set to represent Cyrillic characters, retaining full ASCII compatibility for English text. This made it relatively easy to implement on existing systems without significantly disrupting compatibility.

Despite its age and the rise of Unicode, KOI8-RU remains in use in some legacy systems and is occasionally encountered in older documents or websites. Its structure influenced other Cyrillic encodings, and understanding its characteristics can be helpful when dealing with archival data. While Unicode (specifically UTF-8) is now the preferred standard for encoding text globally, KOI8-RU's historical context and continued presence in some niches warrant its recognition. Its primary competitor in the past was Windows-1251.