HTML Debugging: Table Headers Read Incorrectly

A webpage is not always broken because of a large mistake. Small details can produce exactly this problem: debugging: table headers read incorrectly. This guide shows you what to look for, a concrete fix, and how to check that it worked.

The Idea in Plain English

Complex tables need reliable relationships between data cells and row/column headers through scope, or ids/headers for irregular layouts.

You can test this using a small local HTML file. Change one part at a time and check the result in the browser before adding more code.

A Working Example

The first part shows a problem. The second part shows a safer or more accurate version. Compare them before reading the explanation.

<!-- Problem -->
<table>
    <tr><td>Name</td><td>Score</td></tr>
    <tr><td>Maya</td><td>9</td></tr>
</table>

<!-- Corrected example -->
<table>
    <caption>Quiz results</caption>
    <tr><th scope="col">Name</th><th scope="col">Score</th></tr>
    <tr><th scope="row">Maya</th><td>9</td></tr>
</table>

What Each Part Does

A table represents information arranged in related rows and columns.
A tr represents one row.
A td is an ordinary data cell.

Before the fix, the browser can behave incorrectly or report a warning. After the change, test the exact failure rather than assuming the page is fixed.

Try It Yourself

Navigate by row and column with a screen reader and verify that headings give enough context.

Common Beginner Mistakes

Check the underlying cause before changing unrelated tags.
Changing several parts of the example at once, making it difficult to see which part caused a different result.
Choosing a tag only because its default appearance looks right, without checking whether it describes the content correctly.

Key Takeaways

Complex tables need reliable relationships between data cells and row/column headers through scope, or ids/headers for irregular layouts.
Before the fix, the browser can behave incorrectly or report a warning. After the change, test the exact failure rather than assuming the page is fixed.
Test the markup in a browser, and check accessibility and real-world behavior where relevant.