Image Filenames & Alt Text: Simple Rules

Why images matter for SEO

Images help support written content, improve readability, and provide context. Search engines can’t “see” images in the way humans do, so they rely on textual clues to understand what an image represents.

That’s where filenames and alt text come in.

Image filenames: keep them simple

Before uploading an image, give it a clear, descriptive filename.

For example:

• Poor: IMG_2847.jpg
• Good: on-page-seo-headings-example.jpg

Good filenames use real words, separate words with hyphens, and reflect what the image actually shows. You don’t need to over-optimise — clarity is enough.

What alt text is for

Alt text describes the image for screen readers, provides context if the image fails to load, and helps search engines understand the image’s role.

Alt text is primarily about accessibility, with SEO as a secondary benefit.

How to write good alt text

Good alt text describes what’s in the image, is concise and specific, and fits naturally in a sentence.

For example:

• “Example of an H2 heading used to structure a blog post”

If the image is decorative and adds no meaning, alt text can be left empty.

What to avoid

Avoid:

• Keyword stuffing
• Describing what’s already obvious in surrounding text
• Writing alt text for purely decorative images
• Using the same alt text for multiple images

Alt text should help someone understand the image — nothing more.

A helpful test

If I couldn’t see this image, what would I need to know?

That’s your alt text.