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Character encodings in HTML

use of encoding systems for international characters in HTML

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General referenceInterpretive dossier study · Crown Archives visual atlas
Record originEnglish Wikipedia
Text licenseCC BY-SA 4.0
Source revisionJan 6, 2026
Entity authorityQ184756 ↗
Source-derived summary

While Hypertext Markup Language (HTML) has been in use since 1991, HTML 4.0 from December 1997 was the first standardized version where international characters were given reasonably complete treatment. When an HTML document includes special characters outside the range of seven-bit ASCII, two goals are worth considering: the information's integrity, and universal browser display.

In version 5.3 of the now retired W3C specification, and the current Living Standard published by WHATWG, the only valid encoding is UTF-8.

Specifying the document's character encoding

There are two general ways to specify which character encoding is used in the document.

First, the web server can include the character encoding or "charset" in the Hypertext Transfer Protocol (HTTP) Content-Type header, which would typically look like this:

This method gives the HTTP server a convenient way to alter document's encoding according to content negotiation; certain HTTP server software can do it, for example Apache with the module mod_charset_lite.

Second, a declaration can be included within the document itself.

For HTML it is possible to include this information inside the head element near the top of the document:

HTML5 also allows the following syntax to mean exactly the same:

XHTML documents have a third option: to express the character encoding via XML declaration, as follows:

With this second approach, because the character encoding cannot be known until the declaration is parsed, there is a problem knowing which character encoding is used in the document up to and including the declaration itself. If the character encoding is an ASCII extension then the content up to and including the declaration itself should be pure ASCII and this will work correctly. For character encodings that are not ASCII extensions (i.e. not a superset of ASCII), such as UTF-16BE and UTF-16LE, a processor of HTML, such as a web browser, should be able to parse the declaration in some cases through the use of heuristics.

Editorial summary

Begin with the source’s own compact description: “Character encodings in HTML” is use of encoding systems for international characters in HTML. The dossier treats that line as a proposition to test through Character, encodings and HTML, not as a finished interpretation.

Editorial reviewA dependable orientation record for establishing vocabulary, names and a first evidence trail. The current lead gives the account dated anchors—1991, 1997—that can be checked directly. The selected authority fields contribute no independent date. For this dossier, Character, encodings and HTML is the immediate research focus.
Editorial analysis

Why this record matters

The phrase “use of encoding systems for international characters in HTML” supplies a clear boundary for inquiry. It also exposes the unanswered questions: who defined that boundary, when it became stable and which sources sit outside it.

Evidence profile

Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Jan 6, 2026. The linked authority identifier is Q184756. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1991 and 1997.

Critical limits

The absence of detail may reflect summary conventions rather than a lack of surviving documentation. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.

How to read it

Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.

Best used for
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  • Search vocabulary
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  1. Establish the record: confirm the title “Character encodings in HTML”, its source revision and the description used here.
  2. Expand the search: follow Character encodings in HTML primary sources, Character encodings in HTML archive and Character research across catalogues and specialist indexes.
  3. Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.

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Source & attribution

This entry incorporates text from “Character encodings in HTML” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.