Image SEO: Making Your Pictures Discoverable

WHY IT EXISTS: Search engines are powerful text-processing machines, but they can't "see" images like humans do. Image SEO provides explicit clues—like alt text, filenames, and structured data—to help crawlers understand, index, and rank visual content in Image Search and universal search results.

THE MENTAL MODEL: Think of alt text as a replacement for the image. If the image fails to load, or if a user is using a screen reader, the alt text is what they get. It should accurately and concisely describe the image's content and function. For SEO, it's a primary signal for what the image is about.

HOW IT WORKS: Google uses multiple signals to understand images. First, the alt attribute in an img tag provides a textual description. Second, the filename (e.g., blue-audi-a4-sedan.jpg instead of IMG_1234.jpg) and the surrounding text content on the page provide context. Third, image sitemaps and structured data (like ImageObject) can explicitly tell Google about your images. Finally, file size and format (like WebP) impact page load speed, which is a ranking factor.

WHEN TO USE IT: Always use alt text for any image that conveys information. This includes product photos, diagrams, charts, and photos of people or places. Use descriptive filenames for all images you want to be discoverable. Use image sitemaps when images are loaded via JavaScript or are otherwise hard for crawlers to find.

WHEN NOT TO USE IT: For purely decorative images that add no informational value (e.g., background gradients, stylistic borders), the alt attribute should be present but empty (alt=""). This tells screen readers to ignore the image, preventing auditory clutter. Don't keyword-stuff alt text; it provides a poor user experience and can be seen as spammy.

ONE CANONICAL EXAMPLE: A real estate listing has a photo of a kitchen. Bad: <img src="kitchen1.jpg" alt="kitchen"> Okay: <img src="kitchen-with-granite-countertops.jpg" alt="Modern kitchen with granite countertops and stainless steel appliances."> Best: <img src="123-main-st-kitchen-granite-countertops.jpg" alt="Spacious modern kitchen at 123 Main St. featuring granite countertops, a central island, and stainless steel appliances."> The best example is descriptive, provides context, and uses a helpful filename.