HTML <strong> Tag

The HTML <strong> tag represents strong importance, seriousness, or urgency for its contents.

You can nest <strong> tags to indicate stronger importance. You can use Cascading Style Sheets to make nested tags appear stronger.


The <strong> tag is written as <strong></strong> with the strong text inserted between the start and end tags.

Like this:



The <strong> tag can be used to convey importance in a heading, caption, or paragraph when a certain part needs to be distinguished as the part that really matters from other parts. Like this:


The <strong> tag can be used to convey urgency to content that should be seen sooner than other parts of the document. Like this:


The <strong> tag can also be used to convey seriousness, such as when displaying a caution or warning notice. Like this:

Nesting <strong> Tags

You can nest <strong> tags inside each other. The level of importance is determined by the number of ancestor <strong> tags. Each <strong> element increases the importance of its contents.


Browsers normally display the <strong> element in bold text. However, if you nest <strong> elements, the nested elements probably won't appear any different than the non-nested elements (i.e. where only one <strong> element is used).

You could use CSS to modify the styles of any nested <strong> elements.

Here, I've specified that any <strong> element that is nested inside another <strong> element should be 120% larger than its parent <strong> element.


Attributes can be added to an HTML element to provide more information about how the element should appear or behave.

There are 3 kinds of attributes that you can add to your HTML tags: Element-specific, global, and event handler content attributes.

The <strong> element accepts the following attributes.

Element-Specific Attributes

This table shows the attributes that are specific to the <strong> tag/element.


Global Attributes

The following attributes are standard across all HTML5 elements. Therefore, you can use these attributes with the <strong> tag , as well as with all other HTML tags.

For a full explanation of these attributes, see HTML 5 global attributes.

Event Handler Content Attributes

Event handler content attributes enable you to invoke a script from within your HTML. The script is invoked when a certain "event" occurs. Each event handler content attribute deals with a different event.

Below are the standard HTML5 event handler content attributes.

Again, you can use any of these with the <strong> element, as well as any other HTML5 element.

For a full explanation of these attributes, see HTML 5 event handler content attributes.

Differences Between HTML 4 & HTML 5

HTML 4 defined the <strong> element as indicating emphasis. In particular, it indicated a stronger emphasis than the <em> element.

HTML5 defines the <strong> element as representing strong importance, seriousness, or urgency for its contents.

To see more detail on the two versions see HTML5 <strong> Tag and HTML4 <strong> Tag. Also check out the links to the official specifications below.


Here's a template for the <strong> tag with all available attributes for the tag (based on HTML5). These are grouped into attribute types, each type separated by a space. In many cases, you will probably only need one or two (if any) attributes. Simply remove the attributes you don't need.

Note that the <strong> element does not actually have any local attributes (i.e. attributes that are specific to the element), but the following global attributes and event handlers are available to the element (and all other HTML elements).

For more information on attributes for this tag, see HTML5 <strong> Tag and HTML4 <strong> Tag.

Tag Details

For more details about the <strong> tag, see HTML5 <strong> Tag and HTML4 <strong> Tag.


Here are the official specifications for the <strong> element.

What's the Difference?

W3C creates "snapshot" specifications that don't change once defined. So the HTML5 specification won't change once it becomes an official recommendation. WHATWG on the other hand, develops a "living standard" that is updated on a regular basis. In general, you will probably find that the HTML living standard will be more closely aligned to the current W3C draft than to the HTML5 specification.