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

Typically this element is displayed in italic type. However, it should not be used simply to apply italic styling; use the CSS styling for that purpose. Use the <cite> element to mark the title of a work (book, play, song, etc.); it is also typically styled with italic type, but carries different meaning. Use the <strong> element to mark text that has greater importance than surrounding text.

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.

<i> vs. <em>

It is often confusing to new developers why there are so many elements to express emphasis on some text. <i> and <em> are perhaps one of the most common. Why use <em></em> vs <i></i>? They produce exactly the same result, right?

Not exactly. The visual result is, by default, the same - both tags render its content in italics. But the semantic meaning is different. The <em> tag represents stress emphasis of its contents, while the <i> tag 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>.)

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.

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".

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 (Yes)1 (Yes) (Yes) (Yes)
FeatureAndroidChrome for AndroidEdge mobileFirefox for AndroidIE mobileOpera AndroidiOS Safari
Basic Support (Yes) (Yes) (Yes)4 (Yes) (Yes) (Yes)

See also