HTML 5 defines the fifth major revision of the core language of the World Wide Web, HTML. "HTML 5 differences from HTML 4" describes the differences between HTML 4 and HTML 5 and provides some of the rationale for the changes. This document may not provide accurate information as the HTML 5 specification is still actively in development. When in doubt, always check the HTML 5 specification itself. [ HTML5 ]
This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.
This is a First Public Working Draft produced by the HTML Working Group , part of the HTML Activity . The Working Group intends to publish this document as a Working Group Note to accompany the HTML 5 specification . The appropriate forum for comments is email@example.com , a mailing list with a public archive .
Publication as a Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.
This document was produced by a group operating under the 5 February 2004 W3C Patent Policy . W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy .
HTML has been in continuous evolution since it was introduced to the Internet in the early 1990's. Some features were introduced in specifications; others were introduced in software releases. In some respects, implementations and author practices have converged with each other and with specifications and standards, but in other ways, they continue to diverge.
The HTML 5 draft reflects an effort, started in 2004, to study contemporary HTML implementations and deployed content. The draft:
HTML 5 is still a draft. The contents of HTML 5, as well as the contents of this document which depend on HTML 5, are still being discussed on the HTML Working Group and WHATWG mailing lists. Some of the open issues include (this list is not exhaustive):
HTML 5 is defined in a way that it is backwards compatible with the way user agents handle deployed content. To keep the authoring language relatively simple for authors several elements and attributes are not included as outlined in the other sections of this document, such as presentational elements that are better dealt with using CSS.
User agents, however, will always have to support these older
elements and this is why the specification clearly separates
requirements for authors and user agents. This means that authors
can not use the
element, but user agents are required to support them in a way that
is compatible with how these elements need to behave for
compatibility with deployed content.
Since HTML 5 has separate conformance requirements for authors and user agents there is no longer a need for marking things "deprecated".
The HTML 5 specification will not be considered finished before there are at least two complete implementations of the specification. This is a different approach than previous versions of HTML had. The goal is to ensure that the specification is implementable and usable by designers and developers once it is finished.
The following areas / features defined in HTML 5 are believed to impact the Web architecture:
progresselement, et cetera) instead of an add-on (like the
contentEditablefeature and the
The HTML 5 language has a "custom" HTML syntax that is
compatible with HTML 4 and XHTML 1 documents published on
the Web, but is not compatible with the more esoteric SGML features
of HTML 4, such as
<em/content/ . Documents
this "custom" syntax must be served with the
text/html media type.
HTML 5 also defines detailed parsing rules (including
"error handling") for this syntax which are largely compatible with
popular implementations. User agents must these rules for resources that have the
text/html media type. Here is an example document that
conforms to the HTML syntax:
<!doctype html> <html> <head> <meta charset="UTF-8"> <title>Example document</title> </head> <body> <p>Example paragraph</p> </body> </html>
The other syntax that can be used for HTML 5 is XML. This
syntax is compatible with XHTML1 documents and implementations.
Documents using this syntax need to be served with an XML MIME type
and elements need to be put in the
http://www.w3.org/1999/xhtml namespace following the
rules set forth by the XML specifications. [ XML ]
Below is an example document that conforms to the XML syntax of
HTML 5. Note that XML documents must have an XML MIME type
<?xml version="1.0" encoding="UTF-8"?> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Example document</title> </head> <body> <p>Example paragraph</p> </body> </html>
For the HTML syntax of HTML 5 authors have three means of setting the character encoding:
Content-Typeheader for instance.
metaelement with a
charsetattribute that specifies the encoding as the first element child of the
<meta charset="UTF-8">could be used to specify the UTF-8 encoding. This replaces the need for
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
For the XML syntax authors have to use the rules as set forth in the XML specifications to set the character encoding.
The HTML syntax of HTML 5 requires a
DOCTYPE to be specified to ensure that the browser
renders the page in standards mode. The
DOCTYPE has no other purpose and is therefore optional
for XML. Documents with an XML MIME type are always handled in
standards mode. [ DOCTYPE
DOCTYPE declaration is
<!DOCTYPE html> and is case-insensitive in the
DOCTYPE s from earlier versions
of HTML were longer because the HTML language was SGML based and
therefore required a reference to a DTD. With HTML 5 this is
no longer the case and the
DOCTYPE is only
needed to enable standards mode for documents written using the
HTML syntax. Browsers already do this for
There are a few other syntax changes worthy of mentioning:
langattribute takes the empty string in addition to a valid language identifier, just like
xml:langdoes in XML.
This section is split up in several subsections to more clearly illustrate the various differences there are between HTML 4 and HTML 5.
The following elements have been introduced for better structure:
section represents a generic document or
application section. It can be used together with
h6 to indicate the document structure.
article represents an independent piece of content
of a document, such as a blog entry or newspaper article.
aside represents a piece of content that is only
slightly related to the rest of the page.
header represents the header of a section.
footer represents a footer for a section and can
contain information about the author, copyright information, et
nav represents a section of the document intended
dialog can be used to mark up a conversation like
<dialog> <dt> Costello <dd> Look, you gotta first baseman? <dt> Abbott <dd> Certainly. <dt> Costello <dd> Who's playing first? <dt> Abbott <dd> That's right. <dt> Costello <dd> When you pay off the first baseman every month, who gets the money? <dt> Abbott <dd> Every dollar of it. </dialog>
figure can be used to associate a caption together
with some embedded content, such as a graphic or video:
<figure> <video src=ogg>…</video> <legend>Example</legend> </figure>
Then there are several other new elements:
video for multimedia
content. Both provide an API so application authors can script
their own user interface, but there is also a way to trigger a user
interface provided by the user agent.
are used together with these elements if there are multiple streams
available of different types.
embed is used for plugin content.
mark represents a run of marked text.
meter represents a measurement, such as disk
time represents a date and/or time.
canvas is used for rendering dynamic bitmap
graphics on the fly, such as graphs, games, et cetera.
command represents a command the user can
datagrid represents an interactive representation
of a tree list or tabular data.
details represents additional information or
controls which the user can obtain on demand.
datalist together with the a new
input is used to make comboboxes:
<input list=browsers> <datalist id=browsers> <option value="Safari"> <option value="Internet Explorer"> <option value="Opera"> <option value="Firefox"> </datalist>
eventsource is used to set up a persistent
connection with a server of which messages (events) can be
output represents some type of output, such as from
a calculation done through scripting.
progress represents a completion of a task, such as
downloading or when performing a series of expensive
for marking up ruby annotations.
type attribute now
has the following new values:
The idea of these new types is that the user agent can provide the user interface, such as a calendar date picker or integration with the user's address book and submit a defined format to the server. It gives the user a better experience as his input is checked before sending it to the server meaning there is less time to wait for feedback.
HTML 5 has introduced several new attributes to various elements that were already part of HTML 4:
area elements now have a
media attribute for consistency with the
link element. It is purely advisory.
area elements have a new
ping that specifies a space separated
list of URIs which have to be pinged when the hyperlink is
followed. Currently user tracking is mostly done through redirects.
This attribute allows the user agent to inform users which URIs are
going to be pinged as well as giving privacy-conscious users a way
to turn it off.
area element, for consistency, now has the
base element can now have a
attribute as well, mainly for consistency with the
element (it is also widely supported). Also, the
target attribute for the
area elements is no longer deprecated, as it is useful
in Web applications, e.g. in conjunction with
value attribute for the
is no longer deprecated as it is not presentational. The same goes
start attribute of the
meta element has a
attribute now as this was already widely supported and provides a
nice way to specify the character
encoding for the document.
autofocus attribute can be specified on the
input (except when the
type attribute is
button elements. It provides a declarative way to
focus a form control during page load. Using this feature should
enhance the user experience as the user can turn it off if he does
not like it, for instance.
form attribute for
fieldset elements allows for
controls to be associated with a form (e.g. one they are not a
select elements (as well
datalist element) have a
attribute that allows for automatically prefilling of form
controls, in case of
form , or the form control, in
datalist , with data
from the server.
required attribute applies to
input (except when the
type attribute is
image or some button type such
submit ) and
textarea . It indicates
that the user has to fill in a value in order to submit the
You can now disable an entire
fieldset by using the
disabled attribute on it. This was not possible
input element has several new attributes to
step . As mentioned before it also has a new
list attribute which can be used together with the
menu element has two new attributes:
label . They allow the element
to transform into a menu as found in typical user interfaces as
well as providing for context menus in conjunction with the global
style element has a new
attribute which can be used to enable scoped style sheets. Style
rules within such a
style element only apply to the
script element has a new attribute called
async that influences script loading and
html element has a new attribute called
manifest that points to an application cache manifest
used in conjunction with the API for offline Web applications.
link element has a new attribute called
sizes . It can be used in conjunction with the
icon relationship (set through the
attribute) to indicate the size of the referenced icon.
ol element has a new attribute called
reversed to indicate that the list order is descending
iframe element has two new attributes called
sandbox which allow for
sandboxing content, e.g. blog comments.
Several attributes from HTML 4 now apply to all elements.
These are called global attributes:
There are also several new global attributes:
contenteditableattribute indicates that the element is an editable area. The user can change the contents of the element and manipulate the markup.
contextmenuattribute can be used to point to a context menu provided by the author.
draggableattribute can be used together with the new drag & drop API.
hiddenattribute indicates that an element is not yet, or is no longer, relevant.
data- *collection of author defined attributes. Authors can define any attribute they want as long as they prefix it with
data-to avoid clashes with future versions of HTML. The only requirement on these attributes is that they are not used for user agent extensions.
HTML 5 also makes all event handler attributes from
HTML 4 that take the form
event-name global attributes and adds several new
event handler attributes for new events it defines, such as the
onmessage attribute which can be used together with
eventsource element and the cross-document
These elements have slightly modified meanings in HTML 5 to better reflect how they are used on the Web or to make them more useful:
a element without an
attribute now represents a "placeholder link". It can also contain
flow content rather than being restricted to phrase content.
address element is now scoped by the new
concept of sectioning.
b element now represents a span of text to be
stylistically offset from the normal prose without conveying any
extra importance, such as key words in a document abstract, product
names in a review, or other spans of text whose typical typographic
presentation is emboldened.
hr element now represents a paragraph-level
i element now represents a span of text in an
alternate voice or mood, or otherwise offset from the normal prose,
such as a taxonomic designation, a technical term, an idiomatic
phrase from another language, a thought, a ship name, or some other
prose whose typical typographic presentation is italicized. Usage
varies widely by language.
label element the browser should no longer
move focus from the label to the control unless such behaviour is
standard for the underlying platform user interface.
menu element is redefined to be useful for
small element now represents small print (for
side comments and legal print).
strong element now represents importance rather
than strong emphasis.
The elements in this section are not to be used by authors. User
agents will still have to support them and HTML 5 will get a
rendering section in due course that says exactly how. (The
isindex element for instance is already supported by
The following elements are not in HTML 5 because their effect is purely presentational and therefore better handled by CSS:
The following elements are not in HTML 5 because their usage affected usability and accessibility for the end user in a negative way:
The following elements are not included because they have not been used often, created confusion or can be handled by other elements:
acronymis not included because it has created lots of confusion. Authors are to use
applethas been obsoleted in favor of
isindexusage can be replaced by usage of form controls.
dirhas been obsoleted in favor of
noscript is only conforming in the HTML
syntax. It is not included in the XML syntax as its usage relies on
an HTML parser.
Some attributes from HTML 4 are no longer allowed in HTML 5. If they need to have any impact on user agents for compatibility reasons it is defined how they should work in those scenarios.
In addition, HTML 5 has none of the presentational attributes that were in HTML 4 as they are better handled by CSS:
HTML 5 introduces a number of APIs that help in creating Web applications. These can be used together with the new elements introduced for applications:
HTML 5 has extended the
from DOM Level 2 HTML in a number of ways. The interface is now
implemented on all objects implementing the
Document interface so it stays meaningful in a
compound document context. It also has several noteworthy new
getElementsByClassName() to select elements by
their class name. The way this method is defined it will allow it
to work for any content with
class attributes and a
Document object such as SVG and MathML.
innerHTML as an easy way to parse and serialize an
HTML or XML document. This attribute was previously only available
HTMLElement in Web browsers and not part of any
determine which element is currently focused and whether the
Document has focus respectively.
getSelection() which returns an object that
represents the current selection(s).
execCommand() which are
mostly used for editing of documents.
HTMLElement interface has also gained several
extensions in HTML 5:
getElementsByClassName() which is basically a
scoped version of the one found on
innerHTML as found in Web browsers today. It is
also defined to work in XML context (when it is used in an XML
classList is a convenient accessor for
className . The object it returns exposes methods,
toggle() for manipulating
the element's classes. The
link elements have a similar attribute called
relList that provides the same functionality for the
The changelogs in this section mostly indicate what has been
changed. Rationale for changes can be found in the
mailing list archives and to some extent in the This Week in
HTML 5 series of blog posts. Many editorial and minor
technical changes are not included in these changelogs. If you are
an implementor of HTML 5 you are hereby strongly advised to
follow the specification more closely.
The changes in the changelogs are in rough chronological order to ease editing this document. The changelogs are placed in reverse chronological order.
The changes since the publication on 10 June 2008 are as follows:
ImageDataobjects has been changed from an array to a
canvaselement and its API.
canvashave been made in response to implementation and author feedback. E.g. clarifying what happens when NaN and Infinity are passed and fixing the definitions of
innerHTMLin XML was slightly changed to improve round tripping.
toDataURL()method on the
canvaselement now supports setting a quality level when the media type argument is
posterattribute of the
videoelement now affects its intrinsic dimensions.
typeattribute of the
linkhas been clarified.
linkwhen the expected type is an image.
hrefattribute of the
baseelement does not depend on
xmlnsattribute with the value
http://www.w3.org/1999/xhtmlis now allowed on all HTML elements.
data- *attributes and custom attributes on the
embedelement now have to match the XML
Nameproduction and cannot contain a colon.
volumeon media elements is now 1.0 rather than 0.5.
event-sourcewas renamed to
eventsourcebecause no other HTML element uses a hyphen.
bbhas been added. It represents a user agent command that the user can invoke.
addCueRange()method on media elements has been modified to take an identifier which is exposed in the callbacks.
parentattribute of the
Windowobject is now defined.
embedelement is defined to do extension sniffing for compatibilty with servers that deliver Flash as
text/plain. (This is marked as an issue in the specification to figure out if there is a better way to make this work.)
embedcan now be used without its
getElementsByClassName()is defined to be ASCII case-insensitive in quirks mode for consistency with CSS.
localNameno longer returns the node name in uppercase.
data- *attributes are defined to be always lowercase.
openerattribute of the
Windowobject is not to be present when the page was opened from a link with
topattribute of the
Windowobject is now defined.
aelement now allows nested flow content, e.g. a
divelement, but not itself.
headerelement means to document summaries and table of contents.
autosubmitattribute has been removed from the
insertAdjacentHTML()have been added.
xml:langis now allowed in HTML when
langis also specified and they have the same value. In XML
langis allowed if
xml:langis also specified and they have the same value.
frameElementattribute of the
Windowobject is now defined.
altattribute is omitted a
titleattribute, an enclosing
figureelement with a
legendelement descendant, or an enclosing section with an associated must be present.
irrelevantattribute has been renamed to
definitionURLattribute of MathML is now properly supported. Previously it would have ended up being all lowercase during parsing.
DOCTYPEis allowed for compatibility with XSLT.
inputmodeattribute and seeding of values through an external resource.
load()method on media elements has been redefined as asynchronous. It also tries out files in turn now.
canPlayType()has been added to the media elements.
bufferedBytesattributes have been removed from the media elements.
inputelement gained a
Locationobject gained a
objectelements now partake in form submission.
typeattribute of the
inputelement gained the values
inputelement gained a
multipleattribute which allows for either multiple e-mails or multiple files to be uploaded depending on the value of the
inputelements now have a
novalidateattribute to indicate that the form fields should not be required to have valid values upon submission.
qelement has changed again. Punctation is to be provided by the user agent again.
beforeunloadevents are now defined.
headersattribute pointing to a
tdelement, but authors are required to use
metaelement has a
charsetattribute it must occur within the first 512 bytes.
StorageEventobject now has a
labelelement contains an
inputit may still have a
forattribute as long as it points to the
inputelement it contains.
inputelement now has an
Windowobjects is now defined.
Windowobject gained the
toolbarattributes giving information about the user interface.
The changes since the publication on 22 January 2008 are as follows:
pingattribute have changed.
<meta http-equiv=content-type>is now a conforming way to set the character encoding.
canvaselement has been cleaned up. Text support has been added.
globalStorageis now restricted to the same-origin policy and renamed to
localStorage. Related event dispatching has been clarified.
postMessage()API changed. Only the origin of the message is exposed, no longer the URI. It also requires a second argument that indicates the origin of the target document.
dataTransferobject now has a
typesattribute indicating the type of data being transferred.
melement is now called
figureelement no longer requires a caption.
olelement has a new
queryCommandEnabled()and related methods.
headersattribute has been added for
tableelement has a new
data- nameand can access these through the DOM using
dataset[ name ]on the element in question.
qelement has changed to require punctation inside rather than having the browser render it.
targetattribute can now have the value
showModalDialogAPI has been added.
document.domainAPI has been defined.
sourceelement now has a new
pixelratioattribute useful for videos that have some kind encoding error.
bufferingThrottledDOM attributes have been added to the
beginevent has been renamed to
loadstartfor consistency with the Progress Events specification.
charsetattribute has been added to
iframeelement has gained the
seamlessattributes which provide sandboxing functionality.
rpelements have been added to support ruby annotation.
showNotification()method has been added to show notification messages to the user.
afterprintevents has been added.
The editor would like to thank Ben Millard, Cameron McCormack, Charles McCathieNevile, Dan Connolly, David Håsäther, Frank Ellermann, Henri Sivonen, James Graham, Jürgen Jeka, Maciej Stachowiak, Martijn Wargers, Martyn Haigh, Masataka Yakura, Michael Smith, Olivier Gendrin, Philip Taylor and Simon Pieters for their contributions to this document as well as to all the people who have contributed to HTML 5 over the years for improving the Web!