GlossarySEO
What is an image sitemap?
Also called: image sitemap XML, image:image, image:loc
Definition
An image sitemap is an XML sitemap, or an extension to one, that lists the images on each page with <image:image> and <image:loc> tags, to help Google find images it might miss.
Image sitemap, explained
Google usually finds images through <img> elements in your HTML. An image sitemap helps when it can't, for example with images loaded by JavaScript, or when you want to make sure product screenshots and diagrams are discovered. Google's image sitemap docs say you can either create a separate image sitemap or add image tags to your existing sitemap; both work the same way.
The format is short. Inside each <url> entry, add one <image:image> block per image with an <image:loc> giving the image URL, using the image sitemap namespace. Google allows up to 1,000 <image:image> entries per <url>. Images can live on another domain, such as a CDN, as long as both domains are verified in Search Console and robots.txt allows crawling them.
Several older tags are gone. Google deprecated <image:caption>, <image:title>, <image:geo_location> and <image:license> in 2022. Titles and captions now come from the page itself, so good alt text, filenames and surrounding text matter more than sitemap fields.
For most startups, an image sitemap is optional. If your images are plain <img> elements with real src values, Google will find them. It becomes worth adding if you're relying on Google Images for traffic, like a design tool or a template gallery. In that case, generate it from the same data as the pages so it never lists images that no longer exist.
Why it matters for founders
If images are part of how people find your product, such as templates, screenshots or generated examples, an image sitemap is a cheap way to make sure none are missed.
Example
Your template gallery loads thumbnails with JavaScript. You add <image:image> entries for each template's preview to the gallery sitemap, and more of them appear in Google Images.
Common mistakes
- Still using deprecated tags like
<image:caption>. - Listing images on a CDN domain that isn't verified or is blocked by robots.txt.
- Treating the sitemap as a substitute for alt text.
- Listing images for pages that aren't indexable.
Sources
Checked
Related terms
- XML sitemapAn XML sitemap is a file that lists the URLs you want search engines to crawl and index, optionally with the date each one last changed. It helps discovery; it doesn't guarantee indexing.
- Image SEOImage SEO is making images discoverable and understandable in search and fast to load: HTML image elements, descriptive filenames and alt text, relevant surrounding text, modern formats and sensible sizes.
- Alt textAlt text is the
altattribute on an image that describes it in words. Screen readers read it aloud, browsers show it if the image fails, and search engines use it to understand the image. - Sitemap indexA sitemap index is an XML file that lists other sitemap files instead of pages. It lets large sites split URLs across several sitemaps and submit them all through one file.