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Source-reading note: the exact semantics here come from the HTML element/attribute you chose, not its CSS appearance.
Checkpoint: you can now connect the markup for alternative text and accessible images to a browser behavior and a concrete debugging step.
When this goes wrong, the browser usually keeps rendering. That is what makes the bug easy to miss: recovery can hide a broken source document. In this lesson, the focus is meaningful alt text, decorative images, and complex visual alternatives. That matters because HTML is interpreted by a parser and then exposed to browser features such as navigation, accessibility tooling, form controls, media handling, and script APIs. A correct-looking screenshot can still hide a poor document model.
<img src="chart.png" alt="Orders rose from 120 to 190 between May and June">
Start with the smallest meaningful example. The working snippet demonstrates the core syntax, but the important part is what each piece contributes: the element supplies semantics or behavior, attributes refine that meaning, and surrounding structure gives the browser context. Don't add markup just because a framework or copied example happens to include it.
| Decision | Why it matters |
|---|---|
| Native element | Carries browser semantics and default behavior. |
| Attribute | Refines the element without replacing its meaning. |
| CSS/JS hook | Adds presentation or behavior around the existing structure. |
<img src="hero.jpg" alt="" width="1200"><!-- Empty alt is correct only when the image is decorative. -->
Don't confuse browser-side convenience with a security boundary. The markup in alternative text and accessible images should improve behavior, but authoritative validation and policy belong at the trust boundary that processes the request.
Now put the same idea under pressure. A realistic failure is: Write alternative text for the information the image contributes, not for its pixels. The browser may recover, ignore an invalid combination, or leave the user with a control that appears visually fine but behaves differently than expected. That is why source inspection and keyboard testing belong in the workflow.
A small, explicit HTML decision now is usually cheaper than a compatibility or accessibility workaround later.
Field tip: for alternative text and accessible images, test both the ordinary path and the first case that makes your assumptions false.
Finish the lesson once you have worked through the material. This awards ★ 20 XP.