Windows-1251
Windows-1251 is an 8-bit character encoding, designed to cover languages that use the Cyrillic script such as Russian, Ukrainian, Belarusian, Bulgarian, Serbian Cyrillic, Macedonian and other languages.
| MIME / IANA | windows-1251 |
|---|---|
| Alias(es) | cp1251 (Code page 1251) |
| Language(s) | Russian, Ukrainian, Belarusian, Bulgarian, Serbian Cyrillic, Bosnian Cyrillic, Macedonian, Rotokas, Rusyn, English |
| Created by | Microsoft |
| Standard | WHATWG Encoding Standard |
| Classification | extended ASCII, Windows-125x |
| Other related encoding(s) | Amiga-1251, KZ-1048, RFC 1345's "ECMA-Cyrillic" |
On the web, it is the second most-used single-byte character encoding (or third most-used character encoding overall), and most used of the single-byte encodings supporting Cyrillic. As of January 2024, 0.3% of all websites use Windows-1251. It's by far mostly used for Russian, while a small minority of Russian websites use it, with 94.6% of Russian (.ru) websites using UTF-8, and the legacy 8-bit encoding is distant second. In Linux, the encoding is known as cp1251. IBM uses code page 1251 (CCSID 1251 and euro sign extended CCSID 5347) for Windows-1251.
Windows-1251 and KOI8-R (or its Ukrainian variant KOI8-U) are much more commonly used than ISO 8859-5 (which is used by less than 0.0004% of websites). In contrast to Windows-1252 and ISO 8859-1, Windows-1251 is not closely related to ISO 8859-5.
Unicode (e.g. UTF-8) is preferred to Windows-1251 or other Cyrillic encodings in modern applications, especially on the Internet, making UTF-8 the dominant encoding for web pages. (For further discussion of Unicode's complete coverage, of 436 Cyrillic letters/code points, including for Old Cyrillic, and how single-byte character encodings, such as Windows-1251 and KOI8-R, cannot provide this, see Cyrillic script in Unicode.)