How Alt Tags Help SEO and AEO – And Why Every Image on Your Website Needs One

What is an alt tag?

An alt tag (short for “alternative text”) is a short written description added to an image on a webpage. It tells search engines and assistive technology what an image shows, since neither Google nor a screen reader can actually “see” a photo.

In WordPress, you’ll find the alt text field whenever you upload or edit an image in your media library.

What’s the difference between an alt tag and a title tag?

These two are often confused:

  • Alt tag — the primary text description of an image, used by search engines and screen readers. This is the one that matters most for SEO and accessibility.
  • Title tag — an older attribute previously used by browsers like Internet Explorer to show a tooltip when a user hovered over an image. It has very little SEO value today and is largely considered outdated.

For modern websites, focus your effort on writing good alt text. The title tag is optional.

Why are alt tags important for SEO?

Search engines like Google cannot interpret what’s in a photograph or graphic – they rely entirely on the alt text you provide. Well-written alt tags allow Google to:

  • Index your images and display them in Google Image Search results
  • Better understand the overall topic and context of your page
  • Reward your site with improved rankings for relevant search terms

For businesses on the Mornington Peninsula, this means an image of your shopfront or service in action – properly described with local keywords – can drive extra traffic through Google Images that you’d otherwise miss entirely.

Why are alt tags important for accessibility?

If a visually impaired person visits your website, they may be using a screen reader — software that reads the page aloud. When the screen reader reaches an image, it reads out the alt text in place of the image. Without alt text, the visitor simply hears nothing, or a confusing file name like “IMG_4823.jpg”.

Accessibility is not just good practice – in Australia, websites are expected to meet accessibility standards under the Disability Discrimination Act. Proper alt text is one of the easiest ways to make your site more inclusive.

How do you write a good alt tag?

A good alt tag is:

  • Descriptive and specific — describe what’s actually in the image (“red timber deck overlooking Port Phillip Bay”) rather than something vague (“outdoor area”)
  • Concise — aim for under 125 characters; screen readers often cut off longer descriptions
  • Natural — write it as you would a sentence, not a string of keywords
  • Relevant — include a keyword only if it genuinely describes the image; don’t stuff unrelated terms in

What happens if you leave alt tags empty?

If an image has no alt text, search engines skip it entirely – it’s invisible to them. You miss out on potential image search traffic, and the page may be seen as less thorough or relevant compared to a competitor’s page that is fully optimised.

For decorative images that add no information (like a background pattern or divider), it’s acceptable to use an empty alt tag (alt=””). This tells screen readers to skip it, which is actually the correct approach.

Do alt tags affect my Google ranking?

Yes, indirectly. Alt tags contribute to your overall SEO in several ways: they help Google understand your page content, they can drive traffic through Google Image Search, and they improve accessibility — which is increasingly factored into how Google evaluates page quality. Combined with fast load times and quality content, well-optimised images are a quiet but meaningful part of good SEO.

Need help optimising your website images?

Getting alt tags right across an entire website can be time-consuming, especially if you have a large image library. Contact us now if you need help in optimising your alt tags to help your site rank better on Google.

Alt Tags