SEO, performance, and hosting · Lesson 7 of 8 · 7 minutes

SEO, performance, and hosting: Helpful 404 pages

A useful not-found page offers recovery links, but the server must still return HTTP 404 rather than disguising it as success.

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Your objectives

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1
Build helpful 404 pages
Build this first target: <main>; <h1> inside <main> containing “Page not found”. Inspect the structure before checking the lesson.
Hint & worked example
A useful not-found page offers recovery links, but the server must still return HTTP 404 rather than disguising it as success.
The requested elements, attributes, content, and hierarchy exist outside comments.
```
<main><h1>Page not found</h1></main>
```
Common mistake to avoid: A visual appearance alone guarantees the intended HTML meaning.
2
Extend the helpful 404 pages example
Extend your file to include: <main>; <h1> inside <main> containing “Page not found”; <p> inside <main> containing “The workshop may have moved.”. Inspect the structure before checking the lesson.
Hint & worked example
A useful not-found page offers recovery links, but the server must still return HTTP 404 rather than disguising it as success.
The requested elements, attributes, content, and hierarchy exist outside comments.
```
<main><h1>Page not found</h1><p>The workshop may have moved.</p></main>
```
Common mistake to avoid: Replacing semantic elements with generic divs automatically improves accessibility.
3
Verify the complete helpful 404 pages pattern
Finish the pattern with: <main>; <h1> inside <main> containing “Page not found”; <p> inside <main> containing “The workshop may have moved.”; <a> inside <main> (href="/web/") containing “Return to the Web course”. Inspect the structure before checking the lesson.
Hint & worked example
A useful not-found page offers recovery links, but the server must still return HTTP 404 rather than disguising it as success.
The requested elements, attributes, content, and hierarchy exist outside comments.
```
<main><h1>Page not found</h1><p>The workshop may have moved.</p><a href="/web/">Return to the Web course</a></main>
```
Common mistake to avoid: A visual appearance alone guarantees the intended HTML meaning.

Understand the pattern

A useful not-found page offers recovery links, but the server must still return HTTP 404 rather than disguising it as success.

Misconceptions to reject

A visual appearance alone guarantees the intended HTML meaning.
Replacing semantic elements with generic divs automatically improves accessibility.

The preview is a sanitized subset, not a full browser compatibility test.

Worked example and expected result

<main><h1>Page not found</h1><p>The workshop may have moved.</p><a href="/web/">Return to the Web course</a></main>

A useful not-found page offers recovery links, but the server must still return HTTP 404 rather than disguising it as success.

Try a variation

Adapt the final example to a different project name while retaining its structure and relationships. A different context still needs a real browser and accessibility check.

Explain it

Which statement correctly explains helpful 404 pages?A useful not-found page offers recovery links, but the server must still return HTTP 404 rather than disguising it as success.A visual appearance alone guarantees the intended HTML meaning.Replacing semantic elements with generic divs automatically improves accessibility.

Apply it elsewhere

You reuse helpful 404 pages in a different project. What must still be verified?Nothing; passing a single exercise guarantees every future use.Only whether the source code has the same number of lines.The meaning, relationships, and accessible names in the new document.

Keep the momentum.

Complete the lab, then explain and apply the pattern.

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