How to Optimize Images for SEO

Image optimisation for search has two halves: helping search engines understand what a picture shows, and making sure it does not slow the page down. Both matter, and the second is often ignored.

Descriptive filenames

IMG_4821.jpg tells a crawler nothing. copper-french-press-on-wooden-counter.jpg describes the content in words that could plausibly match a search. Use lowercase and hyphens, keep it short, and describe the picture rather than stuffing keywords into it.

Alt text written for people

Alt text exists so that someone using a screen reader receives the same information a sighted visitor gets. Write what the image actually shows and why it is there. If it is purely decorative, use an empty alt attribute so assistive technology skips it.

Search engines use alt text as a signal precisely because it is meant to be honest. Keyword-stuffed alt text reads badly to users and adds nothing.

Context around the image

Surrounding text, the nearest heading and the caption all help establish what a picture depicts. An image placed under a relevant heading and referenced in the body copy is far easier to interpret than one dropped into a gallery with no context.

Performance is part of it

• Serve modern formats such as WebP where you can.
• Add loading="lazy" to images below the fold, and never to the main hero image.
• Always set width and height so layout does not shift.
• Use srcset so phones do not download desktop-sized files.
• Compress to a sensible quality rather than shipping camera originals.

Structured data and sitemaps

For product, recipe and article pages, include the image URL in your structured data so search engines can associate it with the entity. If images are a significant part of your site, listing them in your sitemap helps discovery, especially for pages where images load through JavaScript.