On-Page SEO · Image SEO

What Is Image SEO?

Images can help or slow your pages. Here is what image SEO is, how to optimise images, what alt text is and how to write it, how to name files, and what compression and next gen formats do.

Updated: July 2026
Written by: Andrew Odgers, Managing Director
Reading time: 9 minutes
The short answer

Image SEO is optimising images so they help rather than slow a page, support accessibility, and can appear in image search. Optimise by sizing, compressing, naming and describing images, and choosing an efficient format. Alt text is a description used by screen readers, written for accessibility first. Name files with short, descriptive, hyphenated words. Compression reduces file size, and next gen formats offer better compression than older ones.

Images that help

What image SEO is, and how to optimise images

Image SEO is optimising the images on your pages so they help rather than slow the page, support accessibility, and can appear in image search, and it covers file size, naming, alt text and format. Because images affect speed, usability and discovery, optimising them is a valuable part of on-page SEO. You optimise images by sizing them appropriately, compressing them, using descriptive file names and alt text, and choosing an efficient format. Small, well-described images work best; because oversized images slow pages and vague ones give no context, optimising each of these areas improves both speed and relevance, which supports overall page performance.

IM 01

Compress

Smaller, faster.

IM 02

Alt text

Accessibility first.

IM 03

Name files

Descriptive, hyphenated.

Alt text, file names, compression and formats

Alt text, naming files, compression, and next gen formats

Alt text is a written description of an image in the HTML, used by screen readers and shown if an image fails to load, and you write it by describing the image clearly and accurately. Because alt text serves accessibility first and gives search engines context second, writing genuine, descriptive text rather than stuffing keywords is the right approach. You name image files with short, descriptive, hyphenated words that reflect what the image shows, rather than default camera file names. Clear names add context; because a descriptive file name helps search engines understand an image, renaming files before uploading is a simple, worthwhile habit. Image compression reduces file size so images load faster without noticeably harming quality, and next gen formats are newer image types that offer better compression than older ones. Both improve speed; because faster images help user experience and performance, compressing images and using an efficient modern format where supported is worthwhile, and it feeds into how users experience your pages.

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Images that load
fast and rank.

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Frequently asked

Image SEO

What is image SEO?
Image SEO is optimising the images on your pages so they help rather than slow the page, support accessibility, and can appear in image search. It covers file size, naming, alt text and format. Because images affect speed, usability and discovery, optimising them is a valuable part of on-page SEO.
How do you optimise images for SEO?
You optimise images by sizing them appropriately, compressing them, using descriptive file names and alt text, and choosing an efficient format. Small, well-described images work best. Because oversized images slow pages and vague ones give no context, optimising each of these areas improves both speed and relevance.
What is alt text and how do you write it?
Alt text is a written description of an image in the HTML, used by screen readers and shown if an image fails to load. You write it by describing the image clearly and accurately. Because alt text serves accessibility first and gives search engines context second, writing genuine, descriptive text rather than stuffing keywords is the right approach.
How should you name image files for SEO?
You name image files with short, descriptive, hyphenated words that reflect what the image shows, rather than default camera file names. Clear names add context. Because a descriptive file name helps search engines understand an image, renaming files before uploading is a simple, worthwhile habit.
What is image compression and what are next gen formats?
Image compression reduces file size so images load faster without noticeably harming quality, and next gen formats are newer image types that offer better compression than older ones. Both improve speed. Because faster images help user experience and performance, compressing images and using an efficient modern format where supported is worthwhile.