ISO/IEC 8859-1

ISO/IEC 8859-1:1998, Information technology—8-bit single-byte coded graphic character sets—Part 1: Latin alphabet No. 1, is part of the ISO/IEC 8859 series of ASCII-based standard character encodings, first edition published in 1987. ISO/IEC 8859-1 encodes what it refers to as "Latin alphabet no. 1", consisting of 191 characters from the Latin script. This character-encoding scheme is used throughout the Americas, Western Europe, Oceania, and much of Africa. It is the basis for some popular 8-bit character sets and the first two blocks of characters in Unicode.

As of April 2025, 1.1% of all web sites use ISO/IEC 8859-1. It is the most declared single-byte character encoding, but as Web browsers and the HTML5 standard interpret them as the superset Windows-1252, these documents may include characters from that set. Some countries or languages show a higher usage than the global average, in 2025 Brazil according to website use, use is at 2.9%, and in Germany at 2.3%.

ISO-8859-1 was (according to the standard, at least) the default encoding of documents delivered via HTTP with a MIME type beginning with text/, the default encoding of the values of certain descriptive HTTP headers, and defined the repertoire of characters allowed in HTML 3.2 documents. It is specified by many other standards. In practice, the superset encoding Windows-1252 is the more likely effective default and it is increasingly common for UTF-8 to work whether or not a standard specifies it.

ISO-8859-1 is the IANA preferred name for this standard when supplemented with the C0 and C1 control codes from ISO/IEC 6429. The following other aliases are registered: iso-ir-100, csISOLatin1, latin1, l1, IBM819, Code page 28591 a.k.a. Windows-28591 is used for it in Windows. IBM calls it code page 819 or CP819 (CCSID 819). Oracle calls it WE8ISO8859P1.