Writing alt text that serves accessibility and SEO

Every image you publish carries a second message. The visible pixels do the heavy lifting for sighted visitors, while a quiet string of text inside the HTML does the same job for everyone else. Alt text, short for alternative text, is that string, and it is one of the rare elements on a page where accessibility and search optimisation point in the exact same direction.

Many small business owners treat image descriptions as an afterthought, especially when they are uploading product photos from a trades van in western Sydney or stock shots snapped at a café in Carlton. The temptation is to skip the field entirely or throw in a half-dozen keywords. Both choices leave value on the table and quietly exclude a slice of the audience that depends on assistive technology.

What alt text actually does

Alt text lives inside the alt attribute of an image tag, and it steps in whenever the image cannot be displayed, fails to load, or is encountered by software that cannot see. Screen readers read it aloud so a person navigating with a keyboard and audio output can understand what is on screen. Search engine crawlers read it to index and categorise the image, which feeds image search results and enriches the surrounding page.

A clean alt attribute is short, descriptive, and written for someone who cannot see the image. It should describe the function or content of the picture, not its visual style. A photo of a plumber tightening a fitting under a kitchen sink needs words that convey the action, the trade, and the location in plain language. Decorative graphics that add nothing meaningful, such as a flourish between paragraphs, should ship with an empty alt attribute so they are correctly skipped by assistive tools.

The accessibility side of the equation

Accessibility is not a fringe concern. In Australia, the Web Content Accessibility Guidelines have shaped federal procurement rules for years, and the Digital Transformation Agency expects public-facing services to meet WCAG 2.1 AA at a minimum. Private operators are not held to the same statutory standard, yet customers with vision impairment still arrive at commercial sites every day, and they spend money where they can navigate without friction.

Screen reader users in Brisbane, Hobart, and Perth rely on alt text the way sighted users rely on captions. A missing or poorly written description can turn a simple task, booking a table or checking a price, into an exercise in frustration. For local businesses, that friction translates into lost bookings. For an e-commerce shop selling anything from surfboards to specialised industrial parts, it translates into abandoned carts.

There is also a quiet human argument for getting it right. A regional photographer in the Barossa Valley who captions every gallery image properly sends a message that she has thought about her audience. A mechanic in Geelong who writes descriptive alt text for each repair gallery shot is doing the same. Accessibility work rarely gets applause, but it builds trust with a segment of the market that talks to other potential customers.

The SEO side most people forget

Search engines have become remarkably good at reading pixels, but they still rely on text to be certain. Alt attributes supply that certainty. When a query points to image results, the descriptive text you provide is one of the strongest signals about what the image actually shows.

For Australian small businesses, this matters more than it might appear at first glance. A tradie trying to win work across a wide catchment, say from the Hills District to the Central Coast, often shows up in image search before the regular blue links. A bakery in Adelaide posting pictures of its cakes can attract foot traffic from travellers searching for the best spot near the Botanic Gardens. None of that happens if every photo carries a filename like IMG_4822.jpg and a missing or stuffed alt attribute.

Local SEO compounds this. Google surfaces nearby businesses for image searches tied to place names, and well-written descriptions help it place the result in the right geographic context. Pair the alt text with structured data and a sensible page title, and the same image starts working as a small acquisition channel rather than dead weight.

Crafting descriptions that actually help

The core rule is simple: describe the image as if you were explaining it to a colleague over the phone. That means naming the subject, the action, and any detail that matters for context. A picture of a woman in a hi-vis vest inspecting scaffolding on a Sydney harbour project should say so. A picture of a flat white beside a window in a Melbourne laneway should mention the flat white, not the abstract composition.

Length matters less than relevance, though most guidance converges on somewhere between eight and twenty words for content images. Anything shorter usually fails to say enough, and anything longer tends to drift into prose the screen reader will read in full.

Practices worth keeping in mind:

• Lead with the subject, then add detail and context.
• Skip filler like "image of", "photo of", or "picture showing".
• Mention brand names and model numbers when they are visible and relevant.
• Treat charts and infographics as data, describing the takeaway, not the visual style.

Phrase each description in the language your customers actually use. A Brisbane pool builder benefits from "concrete plunge pool with timber deck in a suburban backyard" rather than "outdoor installation". An optometrist in Parramatta benefits from "child trying on blue-framed glasses in a practice waiting room" rather than "patient portrait". Specificity serves both accessibility and search at once.

Mistakes that undermine both purposes

Most alt text fails for the same handful of reasons. The first is omission. A small business owner uploads a few dozen product photos and forgets the field on every one, leaving assistive technology with nothing useful to announce and search engines guessing at the file contents.

The second is the "image of" prefix. It adds no information and forces the screen reader to say "image of" before the actual description, which feels clunky and slows comprehension. The third is keyword stuffing, where the alt attribute becomes a tiny list of search terms rather than a sentence. Modern crawlers penalise the practice, and screen reader users find it actively hostile.

A subtler mistake is treating alt text as a caption. Captions live below an image and are visible to everyone. Alt text is invisible until needed, and it should add information rather than repeat what is already on the page. If a photo sits next to a paragraph that begins "Our head chef Marco plates the lemon myrtle dessert at the Adelaide Hills kitchen", the alt text should describe what the image shows, not echo the caption word for word.

A small footnote for projects heavy on documentation: keeping an image library with consistent naming and thoughtful descriptions pays off later. The same discipline that helps a photographer organise shoots or a maker track electronics documentation work can carry over into how alt text is written across a site.

Working alt text into your workflow

Treating alt text as part of the publishing process rather than a finishing touch changes the habit. The simplest way to do that is to make a description mandatory in the upload form, then write it before the image goes live rather than after.

A few habits speed up the work without lowering the quality:

• Draft a one-line summary of each image before uploading it to the CMS.
• Keep a shared phrase bank for repeated subjects, covering staff portraits, workshop shots, and product lines.
• Run a quarterly audit using a crawler that flags missing or suspicious alt attributes.
• Review screen reader output on the most-visited pages once a year.

For sites with large libraries, automation helps but does not replace judgement. Tools can flag empty attributes, detect obvious stuffing, and suggest a starting point based on nearby text, yet a human still needs to decide whether the description captures the right meaning. A thorough record of how a project evolved, similar in spirit to detailed build journal entries, makes it easier to revisit older content and tighten the descriptions when you get a spare afternoon.

The payoff is a website that loads faster for crawlers, reads more clearly for assistive technology, and quietly outperforms competitors who skipped the small step. For Australian businesses competing on local search, that combination is hard to beat, and it costs nothing but a few minutes per image.