The Alt Text Decision Tree: Informative vs Decorative

Writing alt text for images is not about mechanically describing every pixel. Follow W3C's Alt Text Decision Tree:

1. Informative Images: Does the image convey information, data, or context not present in the surrounding text? Write concise, descriptive text: <img src="chart.png" alt="Line graph showing mobile signups increasing 42% in Q3">.
2. Decorative Images: Is the image pure visual eye-candy, background decoration, or redundant with adjacent text? Provide an empty alt attribute: <img src="decorative-flower.svg" alt="">.
   • Notice: Omitting the alt attribute entirely is an error (the screen reader will read the raw file URL like 'image-slash-assets-slash-flower-dot-png'). An empty alt="" instructs the screen reader to silently ignore it.
3. Functional Images (Icons): Is the image inside a button or link? The alt text must describe the action, not the picture: <button><img src="trash.svg" alt="Delete project"></button>.