This is a Commit Snapshot of the standard

This document contains the contents of the standard as of the 0524c68095f5e2941392716caa3367a66ee87fc5 commit, and should only be used as a historical reference. This commit may not even have been merged into the main branch.

Do not attempt to implement this version of the standard. Do not reference this version as authoritative in any way. Instead, see https://www.downtownmelody.com/_x/aHRtbC5zcGVjLndoYXR3Zy5vcmc/ for the living standard.

Table of contents

  1. 1 Introduction
  2. 2 Common infrastructure
  3. 3 Semantics, structure, and APIs of HTML documents
  4. 4 The elements of HTML
  5. 5 Microdata
  6. 6 User interaction
  7. 7 Loading web pages
  8. 8 Web application APIs
  9. 9 Communication
  10. 10 Web workers
  11. 11 Worklets
  12. 12 Web storage
  13. 13 The HTML syntax
  14. 14 The XML syntax
  15. 15 Rendering
  16. 16 Obsolete features
  17. 17 IANA considerations
  18. Index
  19. References
  20. Acknowledgments
  21. Intellectual property rights

Full table of contents

  1. 1 Introduction
    1. 1.1 Where does this specification fit?
    2. 1.2 Is this HTML5?
    3. 1.3 Background
    4. 1.4 Audience
    5. 1.5 Scope
    6. 1.6 History
    7. 1.7 Design notes
      1. 1.7.1 Serializability of script execution
      2. 1.7.2 Extensibility
    8. 1.8 HTML vs XML syntax
    9. 1.9 Structure of this specification
      1. 1.9.1 How to read this specification
      2. 1.9.2 Typographic conventions
    10. 1.10 A quick introduction to HTML
      1. 1.10.1 Writing secure applications with HTML
      2. 1.10.2 Common pitfalls to avoid when using the scripting APIs
      3. 1.10.3 How to catch mistakes when writing HTML: validators and conformance checkers
    11. 1.11 Conformance requirements for authors
      1. 1.11.1 Presentational markup
      2. 1.11.2 Syntax errors
      3. 1.11.3 Restrictions on content models and on attribute values
    12. 1.12 Suggested reading
  2. 2 Common infrastructure
    1. 2.1 Terminology
      1. 2.1.1 Parallelism
      2. 2.1.2 Resources
      3. 2.1.3 XML compatibility
      4. 2.1.4 DOM trees
      5. 2.1.5 Scripting
      6. 2.1.6 Plugins
      7. 2.1.7 Character encodings
      8. 2.1.8 Conformance classes
      9. 2.1.9 Dependencies
      10. 2.1.10 Extensibility
      11. 2.1.11 Interactions with XPath and XSLT
    2. 2.2 Policy-controlled features
    3. 2.3 Common microsyntaxes
      1. 2.3.1 Common parser idioms
      2. 2.3.2 Boolean attributes
      3. 2.3.3 Keywords and enumerated attributes
      4. 2.3.4 Numbers
        1. 2.3.4.1 Signed integers
        2. 2.3.4.2 Non-negative integers
        3. 2.3.4.3 Floating-point numbers
        4. 2.3.4.4 Percentages and lengths
        5. 2.3.4.5 Nonzero percentages and lengths
        6. 2.3.4.6 Lists of floating-point numbers
        7. 2.3.4.7 Lists of dimensions
      5. 2.3.5 Dates and times
        1. 2.3.5.1 Months
        2. 2.3.5.2 Dates
        3. 2.3.5.3 Yearless dates
        4. 2.3.5.4 Times
        5. 2.3.5.5 Local dates and times
        6. 2.3.5.6 Time zones
        7. 2.3.5.7 Global dates and times
        8. 2.3.5.8 Weeks
        9. 2.3.5.9 Durations
        10. 2.3.5.10 Vaguer moments in time
      6. 2.3.6 Legacy colors
      7. 2.3.7 Space-separated tokens
      8. 2.3.8 Comma-separated tokens
      9. 2.3.9 References
      10. 2.3.10 Media queries
      11. 2.3.11 Unique internal values
    4. 2.4 URLs
      1. 2.4.1 Terminology
      2. 2.4.2 Parsing URLs
      3. 2.4.3 Document base URLs
    5. 2.5 Fetching resources
      1. 2.5.1 Terminology
      2. 2.5.2 Determining the type of a resource
      3. 2.5.3 Extracting character encodings from meta elements
      4. 2.5.4 CORS settings attributes
      5. 2.5.5 Referrer policy attributes
      6. 2.5.6 Nonce attributes
      7. 2.5.7 Lazy loading attributes
      8. 2.5.8 Blocking attributes
      9. 2.5.9 Fetch priority attributes
    6. 2.6 Common DOM interfaces
      1. 2.6.1 Reflecting content attributes in IDL attributes
      2. 2.6.2 Using reflect via IDL extended attributes
      3. 2.6.3 Using reflect in specifications
      4. 2.6.4 Collections
        1. 2.6.4.1 The HTMLAllCollection interface
          1. 2.6.4.1.1 [[Call]] ( thisArgument, argumentsList )
        2. 2.6.4.2 The HTMLFormControlsCollection interface
        3. 2.6.4.3 The HTMLOptionsCollection interface
      5. 2.6.5 The DOMStringList interface
    7. 2.7 Safe passing of structured data
      1. 2.7.1 Serializable objects
      2. 2.7.2 Transferable objects
      3. 2.7.3 StructuredSerializeInternal ( value, forStorage [ , memory ] )
      4. 2.7.4 StructuredSerialize ( value )
      5. 2.7.5 StructuredSerializeForStorage ( value )
      6. 2.7.6 StructuredDeserialize ( serialized, targetRealm [ , memory ] )
      7. 2.7.7 StructuredSerializeWithTransfer ( value, transferList )
      8. 2.7.8 StructuredDeserializeWithTransfer ( serializeWithTransferResult, targetRealm )
      9. 2.7.9 Performing serialization and transferring from other specifications
      10. 2.7.10 Structured cloning API
  3. 3 Semantics, structure, and APIs of HTML documents
    1. 3.1 Documents
      1. 3.1.1 The Document object
      2. 3.1.2 The DocumentOrShadowRoot interface
      3. 3.1.3 Resource metadata management
      4. 3.1.4 Reporting document loading status
      5. 3.1.5 Render-blocking mechanism
      6. 3.1.6 DOM tree accessors
    2. 3.2 Elements
      1. 3.2.1 Semantics
      2. 3.2.2 Elements in the DOM
      3. 3.2.3 HTML element constructors
      4. 3.2.4 Element definitions
        1. 3.2.4.1 Attributes
      5. 3.2.5 Content models
        1. 3.2.5.1 The "nothing" content model
        2. 3.2.5.2 Kinds of content
          1. 3.2.5.2.1 Metadata content
          2. 3.2.5.2.2 Flow content
          3. 3.2.5.2.3 Sectioning content
          4. 3.2.5.2.4 Heading content
          5. 3.2.5.2.5 Phrasing content
          6. 3.2.5.2.6 Embedded content
          7. 3.2.5.2.7 Interactive content
          8. 3.2.5.2.8 Palpable content
          9. 3.2.5.2.9 Script-supporting elements
          10. 3.2.5.2.10 select element inner content elements
          11. 3.2.5.2.11 optgroup element inner content elements
          12. 3.2.5.2.12 option element inner content elements
        3. 3.2.5.3 Transparent content models
        4. 3.2.5.4 Paragraphs
      6. 3.2.6 Global attributes
        1. 3.2.6.1 The title attribute
        2. 3.2.6.2 The lang and xml:lang attributes
        3. 3.2.6.3 The translate attribute
        4. 3.2.6.4 The dir attribute
        5. 3.2.6.5 The style attribute
        6. 3.2.6.6 Embedding custom non-visible data with the data-* attributes
      7. 3.2.7 The innerText and outerText properties
      8. 3.2.8 Requirements relating to the bidirectional algorithm
        1. 3.2.8.1 Authoring conformance criteria for bidirectional-algorithm formatting characters
        2. 3.2.8.2 User agent conformance criteria
      9. 3.2.9 Requirements related to ARIA and to platform accessibility APIs
  4. 4 The elements of HTML
    1. 4.1 The document element
      1. 4.1.1 The html element
    2. 4.2 Document metadata
      1. 4.2.1 The head element
      2. 4.2.2 The title element
      3. 4.2.3 The base element
      4. 4.2.4 The link element
        1. 4.2.4.1 Processing the media attribute
        2. 4.2.4.2 Processing the type attribute
        3. 4.2.4.3 Fetching and processing a resource from a link element
        4. 4.2.4.4 Processing `Link` headers
        5. 4.2.4.5 Early hints
        6. 4.2.4.6 Providing users with a means to follow hyperlinks created using the link element
      5. 4.2.5 The meta element
        1. 4.2.5.1 Standard metadata names
        2. 4.2.5.2 Other metadata names
        3. 4.2.5.3 Pragma directives
        4. 4.2.5.4 Specifying the document's character encoding
      6. 4.2.6 The style element
      7. 4.2.7 Interactions of styling and scripting
    3. 4.3 Sections
      1. 4.3.1 The body element
      2. 4.3.2 The article element
      3. 4.3.3 The section element
      4. 4.3.4 The nav element
      5. 4.3.5 The aside element
      6. 4.3.6 The h1, h2, h3, h4, h5, and h6 elements
      7. 4.3.7 The hgroup element
      8. 4.3.8 The header element
      9. 4.3.9 The footer element
      10. 4.3.10 The address element
      11. 4.3.11 Headings and outlines
        1. 4.3.11.1 Heading levels & offsets
        2. 4.3.11.2 Sample outlines
        3. 4.3.11.3 Exposing outlines to users
      12. 4.3.12 Usage summary