HTML Guides for summary

The <summary> element serves as the clickable disclosure toggle for a <details> element. Because its built-in behavior is inherently interactive — clicking it expands or collapses the parent <details> content — the HTML specification assigns it an implicit button role. This means assistive technologies like screen readers already announce <summary> as a button without any additional markup.

When you explicitly add role="button" to a <summary> element, the W3C validator flags it as unnecessary. While this doesn’t cause functional problems, redundant ARIA roles are discouraged by the first rule of ARIA use: if an HTML element already has the semantics you need, don’t re-add them with ARIA attributes. Redundant roles add noise to your code, can confuse other developers into thinking custom behavior is being applied, and in edge cases may interact unexpectedly with certain assistive technologies.

This principle applies broadly — many HTML elements have implicit roles (e.g., <nav> has navigation, <main> has main, <button> has button). Adding the role they already carry is always unnecessary.

How to fix it

Remove the role="button" attribute from the <summary> element. No replacement is needed since the semantics are already built in.

Examples

❌ Incorrect: redundant role="button" on <summary>

<details>
  <summary role="button">Show more information</summary>
  <p>Here is the additional information that was hidden.</p>
</details>

The validator will report: The “button” role is unnecessary for element “summary”.

✅ Correct: <summary> without an explicit role

<details>
  <summary>Show more information</summary>
  <p>Here is the additional information that was hidden.</p>
</details>

The <summary> element’s implicit button role ensures assistive technologies already treat it as an interactive control. No additional attributes are required.

✅ Correct: a more complete <details> example

<details>
  <summary>I have keys but no doors. I have space but no room. You can enter but can't leave. What am I?</summary>
  <p>A keyboard.</p>
</details>

Clicking the <summary> toggles the parent <details> element between its open and closed states. Screen readers announce it as a button automatically, and keyboard users can activate it with <kbd>Enter</kbd> or <kbd>Space</kbd> — all without any explicit ARIA role.

To resolve the W3C Validator issue regarding the obsolete summary attribute on the table element, you should remove the summary attribute and instead provide a description of the table structure using a caption element.

Here’s how you can fix it:

• Remove the summary attribute: This attribute is no longer supported in modern HTML standards.
• Add a caption element: This element gives a brief description of the table, making it accessible and informing users what the table represents.

Example Before and After

Before Fixing (with obsolete summary attribute)

<table summary="This table shows the sales data for the year.">
    <tr>
        <th>Month</th>
        <th>Sales</th>
    </tr>
    <tr>
        <td>January</td>
        <td>$1000</td>
    </tr>
    <tr>
        <td>February</td>
        <td>$1200</td>
    </tr>
</table>

After Fixing (with caption element)

<table>
    <caption>Sales Data for the Year</caption>
    <tr>
        <th>Month</th>
        <th>Sales</th>
    </tr>
    <tr>
        <td>January</td>
        <td>$1000</td>
    </tr>
    <tr>
        <td>February</td>
        <td>$1200</td>
    </tr>
</table>

Additional Option: Using a figure Element

If you want to provide a more extensive description alongside your table, you can wrap the table in a figure element.

Example with figure

<figure>
    <figcaption>Sales Data for the Year</figcaption>
    <table>
        <tr>
            <th>Month</th>
            <th>Sales</th>
        </tr>
        <tr>
            <td>January</td>
            <td>$1000</td>
        </tr>
        <tr>
            <td>February</td>
            <td>$1200</td>
        </tr>
    </table>
</figure>