Image alt text is a text alternative associated with an image in HTML. Its primary purpose is to communicate useful image information to people who cannot see the image or whose browser does not display it. It can also help search engines interpret an image in the context of the surrounding page. Good alt text therefore starts with the image’s purpose, not a list of keywords you want to rank for.
For a small business website, useful alt text can make portfolio pages, service explanations and product imagery more understandable. But not every image needs a long description. A decorative flourish should not distract a screen-reader user with irrelevant wording, while an image that communicates a real detail should have an appropriate text alternative.
TL;DR
- Describe the relevant information or function of the image, not every visual detail.
- Use empty alt text (alt="") for purely decorative images when appropriate.
- Keep wording concise and contextual; do not stuff keywords into the attribute.
- For linked images, explain the link’s purpose if the image is the only link content.
- Compress images and provide clear filenames, but treat these as separate tasks from alt text.
What is alt text for?
Alt text provides a text alternative for an image when that alternative is needed to understand the page or use a control. For example, if a project gallery shows a redesigned restaurant website, text such as “Mobile homepage for a restaurant showing menu and booking links” describes the image’s relevant purpose. “Image of website” is vague, while a long inventory of every visual colour and object may be unnecessary.
Google’s image guidance explains that it uses alt text alongside page content and computer-vision systems to understand image subject matter. The accessibility role remains essential: alt text should help people, including screen-reader users, understand content and controls. SEO should follow from accurate descriptions, not replace them.
How to write useful image alt text
1. Identify the image’s purpose in context
Ask what the reader would lose if they could not see the image. If the image shows a specific step in a tutorial, describe the step. If it shows a genuine client project, state what is being demonstrated, without disclosing confidential information or making unsupported claims about results.
The same image can require different alt text depending on where and why it is used. A photograph used as an example of a mobile navigation problem might need to identify that problem. The same image used as decorative background artwork may not need a text alternative at all.
2. Be concise and specific
Describe the important subject in natural language. Avoid starting every image description with “image of” or “picture of” unless that wording adds context. There is no need to hit an artificial character count; include enough information for the user to understand the image’s relevance and remove filler.
3. Do not insert keywords that the image does not show
If the image shows a laptop with a website audit, do not claim it shows a “leading UK SEO agency’s proven ranking results” unless that is both accurate and directly supported. Keyword stuffing is unhelpful to users and can make the page appear spammy. Alt text should represent the image, not act as hidden ad copy.
4. Decide whether an image is informative or decorative
Decorative images usually do not add information beyond nearby text. For a decorative line, shape or background flourish, empty alt text can help assistive technology skip it. Do not omit alt text attributes randomly; an empty value and a missing value can have different effects on how some assistive technologies treat an image.
5. Treat linked images carefully
If an image is the only content inside a link, the alternative should convey the purpose of the link. For example, if a logo links to the homepage, the alt text can identify the brand and homepage destination. If a portfolio thumbnail links to a case study, explain which project the link opens rather than describing decorative details alone.
Image alt text examples
Useful for a project image:
alt="Mobile homepage for a local plumbing business showing emergency repair contact options"
Useful for a chart:
alt="Bar chart comparing organic clicks across four months"
Useful for a linked portfolio image:
alt="View the redesign case study for a dental practice website"
Decorative image:
alt=""
These are examples, not text to copy onto every image. Check whether the wording accurately reflects the actual image and the purpose of the page.
Pro Tip: Write alt text after you know what the image contributes to the article. If the image is only a decorative background, an SEO keyword phrase is not a reason to make it verbose.
Common image accessibility and SEO mistakes
Repeating the page keyword in every image
An article about local SEO might contain screenshots, icons and decorative images. They do not all need to say “local SEO UK small business”. Describe what each useful image contributes, and leave decorative images empty where suitable.
Writing alt text for stock photos as if they prove a result
A stock photograph of a smiling business owner does not demonstrate client success, satisfaction or revenue growth. Do not describe illustrative photography as evidence of an outcome.
Using a filename as the alt text
A file called website-speed-audit.png may be a useful descriptive filename, but the alt attribute should describe the visual or function for people using assistive technology. File naming and alt text serve related but different purposes.
Using alt text to repeat captions
If a caption already gives a key fact, consider whether the alt text should describe a different visual detail or whether the image is redundant with the nearby text. Avoid making the same long explanation play twice for screen-reader users when it adds no value.
Forgetting image quality and page performance
Alt text does not make a large image load faster. Choose appropriate dimensions, compress files, consider modern formats and use responsive images where appropriate. Keep the image close to relevant page content and provide an informative filename when practical.
How to audit images on your site
Crawl important pages and export image URLs and alt attributes. Look for missing attributes, generic filenames, repeated keyword-heavy descriptions and oversized image files. Then inspect each image in context. Automated tools can locate possible problems, but they cannot reliably determine the right description for every image without understanding what the image communicates.
Start with meaningful visuals on high-value service pages, portfolio pages and tutorials. Document the reason for each decision: informative image, functional image or decorative asset. This makes later content updates more consistent.
How The Super Shoppe can help
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