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The HTML <em> element marks text that has stress emphasis. The <em> element can be nested, with each level of nesting indicating a greater degree of emphasis.

Content categories Flow content, phrasing content, palpable content
Permitted content Phrasing content.
Tag omission None, both the starting and ending tag are mandatory.
Permitted parents Any element that accepts phrasing content.
Permitted ARIA roles Any
DOM interface HTMLElement Up to Gecko 1.9.2 (Firefox 4) inclusive, Firefox implements the HTMLSpanElement interface for this element.

Attributes

This element only includes the global attributes.

Usage notes

The <em> element is for words that have a stressed emphasis compared to surrounding text, which is often limited to a word or words of a sentence and affects the meaning of the sentence itself.

Typically this element is displayed in italic type. However, it should not be used simply to apply italic styling; use the CSS font-style property for that purpose. Use the <cite> element to mark the title of a work (book, play, song, etc.). Use the <i> element to mark text that is in an alternate tone or mood, which covers many common situations for italics such as scientific names or words in other languages. Use the <strong> element to mark text that has greater importance than surrounding text.

<i> vs. <em>

New developers are often confused at seeing multiple elements that produce similar results. <em> and <i> are a common example, since they both italicize text. What's the difference? Which should you use?

By default, the visual result is the same. However, the semantic meaning is different. The <em> element represents stress emphasis of its contents, while the <i> element represents text that is set off from the normal prose, such a foreign word, fictional character thoughts, or when the text refers to the definition of a word instead of representing its semantic meaning. (The title of a work, such as the name of a book or movie, should use <cite>.)

This means the right one to use depends on the situation. Neither is for purely decorational purposes, that's what CSS styling is for.

An example for <em> could be: "Just do it already!", or: "We had to do something about it". A person or software reading the text would pronounce the words in italics with an emphasis, using verbal stress.

An example for <i> could be: "The Queen Mary sailed last night". Here, there is no added emphasis or importance on the word "Queen Mary". It is merely indicated that the object in question is not a queen named Mary, but a ship named Queen Mary. Another example for <i> could be: "The word the is an article".

Example

The <em> element is often used to indicate an implicit or explicit contrast.

<p>
  In HTML 5, what was previously called
  <em>block-level</em> content is now called
  <em>flow</em> content.
</p>

Result

In HTML 5, what was previously called block-level content is now called flow content.

Specifications

Specification Status Comment
HTML Living Standard
The definition of '<em>' in that specification.
Living Standard  
HTML5
The definition of '<em>' in that specification.
Recommendation  
HTML 4.01 Specification
The definition of '<em>' in that specification.
Recommendation  

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support1 Yes1 Yes Yes Yes
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support Yes Yes Yes4 Yes Yes Yes

See also