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.

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.