Alt Text for Website Images: A Practical Guide for Small Businesses

Upload an image to a website editor and you will often see a field labelled Alt Text, Alternative Text or simply ALT.

What are you supposed to put there?

A literal description of everything in the photograph?

Your main SEO keyword?

The image filename?

A full sentence?

Or nothing at all?

The most useful answer starts with a different question:

Why is this image on this particular page?

Alt text is not simply a caption hidden behind an image. Its job is to provide a useful text alternative when the image cannot be perceived in the usual visual way.

That means good alt text depends on purpose and context, not just what the camera captured.

What Is Alt Text?

For a normal image placed on a web page using an HTML image element, alternative text is provided through the image's alt attribute.

Website builders often hide the HTML and simply give you an Alt Text box.

The text you enter can help people who use assistive technology such as screen readers understand information that would otherwise only be available visually.

Alt text can also help search systems understand an image. Google says it uses alt text together with the page's content and computer-vision systems when interpreting image subject matter.

That does not mean alt text is a ranking trick.

Adding a keyword to every image does not guarantee better rankings or Google Images visibility, and adding alt text does not make an otherwise inaccessible website accessible.

Think of alt text first as a text alternative for the useful meaning of an image.

Start With the Image's Purpose

Imagine a hypothetical plumbing business has a photograph showing a technician repairing a burst pipe beneath a kitchen sink.

What should the alt text say?

That depends on where the photograph appears.

On a page about emergency leak repairs, the important meaning might be:

Plumber repairing a burst pipe beneath a kitchen sink

On an About page where the photograph is introducing a specific team member, the important information could instead be:

Thabo Mokoena repairing a customer's kitchen pipe

If that same photograph appears beside a paragraph that already says, “Our plumbers repair burst pipes, leaking taps and damaged household pipework,” the photograph might add little information at all.

The pixels have not changed.

The context has.

That is why copying one alt-text description everywhere an image appears is not always appropriate.

Which Images Normally Need Useful Alt Text?

A useful starting point is to ask:

Would someone miss important information, meaning or function if this image disappeared?

If the answer is yes, the image normally needs an appropriate text alternative.

Examples may include:

· a photograph showing a product feature being discussed in the text;

· an image of a completed project when the visual result is part of the evidence;

· a photograph identifying a staff member;

· an image showing the location or entrance a customer needs to recognise;

· a simple diagram communicating information;

· an icon whose meaning is not otherwise given in text;

· or an image being used as a link or button.

The description should communicate what matters about the image for that situation.

It does not need to catalogue every visible object.

For example, if a hypothetical landscaper is showing the finished result of a paving project, this:

Completed grey paving installation around a residential swimming pool

is more useful than:

Image of a house, blue sky, pool, paving, plants, wall and garden furniture

The first version communicates why the image belongs on the page.

Decorative Images Are Different

Some images are included purely for visual appearance.

They may add colour, atmosphere or spacing without adding information the reader needs.

Examples could include:

· a decorative background pattern;

· a visual flourish between sections;

· an abstract texture;

· or a generic supporting photograph whose message is already fully expressed by nearby text.

For an ordinary HTML image that is genuinely decorative, accessibility guidance recommends an empty alt value so assistive technology can ignore it.

In code, that is:

alt=""

An empty alt value is not the same as forgetting the alt attribute altogether.

If the attribute is simply missing, some assistive technologies may announce the filename or other unhelpful information.

So “decorative” does not mean “we forgot to fill in the field.”

It is a deliberate decision that the image does not contribute useful information in that context.

Surrounding Text Can Change the Decision

Nearby text matters.

Suppose a small-business website includes a photo of a delivery van. Directly underneath it is the visible caption:

Our refrigerated delivery vehicle serving Johannesburg and Pretoria

If the image adds no information beyond that caption, repeating the entire sentence in the alt text may create unnecessary repetition for someone using a screen reader.

In another context, however, the photograph may show information that the surrounding copy does not mention—for example, the vehicle's wheelchair lift, branded identification or unusual equipment relevant to the page.

Then that useful difference may belong in the alternative text.

A good test is:

If the image were replaced by my alt text while someone read the surrounding page, would they receive the information that matters without hearing unnecessary repetition?

The Same Image Can Need Different Alt Text

This is one of the most useful principles to remember.

W3C accessibility guidance gives examples where the same visual image can require different text alternatives according to how it functions in different places.

Consider a hypothetical photo of a bakery storefront.

Context 1: Contact page

The photograph is helping customers recognise the entrance.

Useful alt text might be:

Street entrance to Sunrise Bakery beside the pharmacy

Context 2: About page

The photograph supports a paragraph about the business premises.

Useful alt text might be:

Sunrise Bakery's customer counter and street-facing shop

Context 3: Decorative banner

The page already identifies the bakery and the photograph adds no further information.

The appropriate alternative may be empty.

There is therefore no universal “correct alt text” permanently attached to the photograph.

The right alternative belongs to the image in context.

Write for Meaning, Not for a Visual Inventory

One common mistake is describing images mechanically.

For example:

Woman standing in room wearing blue shirt holding black tablet beside table

That may be visually accurate but still unhelpful.

Suppose the photo appears on the About page of a bookkeeping firm and identifies its owner.

The more useful version could be:

Naledi Dlamini, owner of Example Bookkeeping

If the tablet, shirt and table have no importance to the page, they do not need to be narrated.

Alt text is usually strongest when it communicates the useful meaning, not every visual detail.

Keep It Concise—but Give Enough Information

There is no useful rule saying every alt description must contain exactly a certain number of characters or words.

Aim instead for the shortest description that communicates what the reader needs from that image.

For a straightforward image, that may be only a few words:

Chocolate birthday cake with floral icing

Another image may need slightly more context:

Solar panels installed across the north-facing roof of a two-storey home

Do not make the description longer merely to sound thorough.

And do not cut out important information merely to meet an arbitrary character count.

Avoid “Image of” and “Picture of” Unless It Adds Meaning

Screen readers generally identify that an image is present.

So descriptions such as:

Image of a plumber repairing a pipe

usually gain nothing from the words “image of.”

You can simply write:

Plumber repairing a leaking copper pipe

There are exceptions where the type of image itself matters.

For example:

Historical photograph of the original shopfront in 1978

Here, knowing that it is a historical photograph contributes useful context.

Use judgement rather than a rigid wording formula.

Do Not Stuff Keywords Into Alt Text

Alt text should not become a hidden list of search phrases.

Something like:

Cape Town plumber plumbing services Cape Town emergency plumber best plumber plumbing repairs plumber near me

does not serve a useful accessibility purpose.

It also contradicts Google's own guidance. Google advises writing useful, contextually appropriate alt text and specifically warns against filling alt attributes with keywords.

If an ordinary phrase relevant to the page naturally belongs in the description, that is fine.

For example:

Emergency plumber repairing a burst pipe in a Cape Town apartment

may be appropriate if the location genuinely matters to the image and page.

The goal is still to describe the useful meaning—not to squeeze search phrases into every photograph.

Do Not Use the Filename as the Alt Text

IMG_4837.jpg is not meaningful alternative text.

Neither is:

plumber-service-photo-final-2.webp

File naming and alt text are different decisions.

A useful alternative should be written for the person encountering the image in context, not copied from whatever name the file happened to receive when it was uploaded.

What About Images That Contain Words?

Sometimes important information appears inside an image itself.

For example, a graphic might contain:

Closed Monday — Open Tuesday to Saturday, 08:00–17:00

If that information is not available as ordinary page text elsewhere, someone who cannot perceive the graphic still needs access to the important message.

For a simple image of text, the text alternative may need to communicate those words.

A better website-content decision, where practical, is often to provide important information as real text on the page rather than relying only on an image.

Complex posters, charts or detailed diagrams may need more information than can sensibly fit into short alt text. That becomes a broader accessibility-content decision beyond this practical guide.

Functional Images Need Their Purpose Explained

An image can also perform an action.

For example, imagine a shopping-cart icon is the only content inside a button.

The useful alternative is not necessarily:

Shopping trolley icon

The visitor needs to know what the control does:

View cart

Likewise, a magnifying-glass image used as the only content in a search button should communicate Search, rather than simply describing a magnifying glass.

In other words, when the image functions as a control, describe the purpose or action.

A Practical Alt-Text Decision Process

For each website image, ask these questions in order:

1. Does this image communicate information the reader needs?

If yes, identify that useful information.

2. Is the same information already clearly provided by nearby text?

If yes, avoid unnecessary repetition.

3. Is the image purely decorative in this context?

If yes, it may need an empty alternative rather than a description.

4. Is the image itself a button or link?

If yes, communicate the action or destination.

5. What would I tell someone who could not see the image so that this part of the page still made sense?

Write that, concisely.

Then read the paragraph and the alt text together.

Does the result sound useful?

Or does it repeat the page, list irrelevant visual details, or read like SEO keywords?

Review Alt Text When Images Move to New Pages

Alt text should not always be treated as permanent image metadata.

If an image moves from a service page to an About page, gallery or contact page, its role may change.

When reusing images, ask again:

Why is this image here now?

That small review helps prevent websites from accumulating descriptions that technically exist but no longer match the content.

Alt Text Is One Part of a Better Website

Useful alt text can make important image information available in text form and can help search systems understand image context.

But it is one part of a much bigger picture.

Website accessibility also involves areas such as headings, contrast, keyboard operation, forms, captions, link text and other design and technical decisions.

Likewise, image performance involves file size, dimensions and delivery choices that alt text does not solve.

Do not use an alt-text checklist as proof that the whole website is accessible, technically optimised or likely to rank.

For the image in front of you, the job is simpler:

Decide what the image contributes, then provide the text alternative that best preserves that meaning—or deliberately provide no spoken description when the image is genuinely decorative.

If you need help reviewing website images, content or broader accessibility issues, WebWise Management can help assess what information your website is communicating and where practical improvements are needed.

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