For example, the code might say: <img src="whatever.gif" alt="Two cute kittens are playing on a blanket">

If you are blind, you get an idea of what's being conveyed by that image. If you're on a train and the WiFi craps out just before the image loads, you'll also benefit! If the image is of text in a language you don't read, your device can translate it for you.

The alt text can be as long or as short as is necessary. It might just be "kid giving a thumbs up" or it could be incredibly detailed. Here's how the BBC's Newsbeat typically adds alt text for younger viewers:

Is that too much? Maybe. It depends on your audience. For partially sighted kids who crave the same pop information as their sighted peers, I think it is great.

So alt text is a good thing. But people are lazy and don't always write it. Perhaps the answer is to embed alt text inside image metadata?

It's a lovely idea - and technically feasible - but it fails to account for user needs.

And that brings me to the point of this post. Who is your alt text for? What information are you trying to share?

Here's a good example. I looked at a bunch of popular memes which had alt-text pre-populated in them. Here's what they said:

Terence Eden

@Edent@mastodon.social

Whenever people talk about embedding alt text into images, I remember that lots of gif search services already try to do that.

Here's BlueSky's gif service. I searched for some popular memes. Each had alt-text baked in.

Take a look and tell me if you think that the embedded text conveys the sentiment of the image? If you couldn't see the animation, would you understand what was going on from that alt?

2025-09-07, 21:11 12 boosts 22 favorites

OK, so sometimes the captioner makes a mistake and thinks the Chuckle Brothers are kissing (WTF?!) perhaps we can excuse that as being an obscure image. But the "idiot sandwich" one is inexcusable. It's a popular meme with a specific meaning.

Which leaves me with a few questions for you:

• If you saw that the image you were sharing had crap alt text - would you bother editing it?
• Is bad alt text worse than no alt text?
• Can the same image have multiple meanings?
• Have you spent any time browsing the web with images turned off? Did you enjoy it?

You can find out more about Alt Text on the RNIB site.

The WordPress Media Library lets you set the alt text of an image. But, crucially, this alt text can be different when the image is used as a featured image.

Here's how to find all your featured images which don't have alt text.

One Liner

Paste this into wp shell to get a list.

foreach (get_posts( array( 'post_type' => 'post', 'post_status' => array('publish'), 'posts_per_page' => -1,) ) as $post) { if( simplexml_load_string( get_the_post_thumbnail($post) )["alt"] == "") { echo $post->post_date . " " . get_site_url(). "/wp-admin/post.php?post=" . $post->ID . "&action=edit " . $post->post_title . "\n"; } }

An explanation

To get the image element of the featured image, use get_the_post_thumbnail(1234); That will spit back:

<img width="800" height="400" 
     src="https://example.com/test.png"
     class="attachment-post-thumbnail size-post-thumbnail wp-post-image"
     alt="This is some alt text."
     decoding="async" loading="lazy" />"

If there's no alt, you'll see alt="".

Getting an attribute out of a scrap of HTML is simple. We're going to be naughty and pretend this is XML. Shhh! Don't tell the W3C!

$xml = simplexml_load_string( get_the_post_thumbnail(1234) );

The alt text can be retrieved with:

$alt = $xmlEl["alt"];

So anything where $xmlEl["alt"] == "" is an image without alt text.

Finally, the code generates a link to the edit page of the post.

For example <img src="monalisa.jpg" alt="A painting of the Mona Lisa.">

Most social networks will let users add alt text to help describe their images. Brilliant!

But... People don't always add alt text when they upload an image. They may not realise it is helpful, or they don't know how to write a good description, or they may not have time to write something suitable. This leads to a frequently asked question: "Should I embed the alt text inside the image file? That way, whenever people share the image the alt text will automatically be attached!"

Here's my attempt to answer that.

Short answer

No.

Long answer

Nooooooooooooo!

Reasoned Answer

It is complicated.

On a technical level, yes. Most modern image formats allow you to add image metadata - known as EXIF. This EXIF commonly contains GPS location, timestamps, make and model of camera, etc. Here's an example from one of my photos:

There are a pre-defined list of acceptable EXIF tags one of which is "ImageDescription", which is defined as:

A character string giving the title of the image. It may be a comment such as "1988 company picnic" or the like. Two-byte character codes cannot be used. When a 2-byte code is necessary, the Exif Private tag UserComment is to be used.

So, there you have it. Yes you can embed text inside an image. With the right software you can read it. So, technically, you can stuff alt text in there and have a website automatically add it to the alt attribute.

But this is only half the story. What an image represents is highly context dependent.

In her article about using AI to automatically provide image captions, Léonie Watson makes that point that alt text needs to be:

provided by a content author who knows exactly what's in the image, why its being used and the context its being used in.

Take this very real photo of a famous actress who I just got an AI to dream up.

What's a suitable alt text for this image?

• Famous actress Claire Flumptron standing on the red carpet.
• Claire Flumptron shows off her brand new arm tattoo which has strange mystic runes covering her forearm.
• Designer Giovanni Tuccini's new red dress has a small strap over the shoulder.
• AI image where the hand is strangely deformed and the neck looks twisted beyond human endurance.
• Smiling woman with cropped blonde hair and heavy eye makeup.
• Last known photo of the Mayor (right). His blurry face is smiling.
• ...

There's no "right" answer. It depends on what the image is being used to illustrate.

A picture may be worth a thousand words. But those thousand words depend on context.

Update Here's another good example of embedded alt text failing badly.

Terence Eden

@Edent@mastodon.social

Whenever people talk about embedding alt text into images, I remember that lots of gif search services already try to do that.

Here's BlueSky's gif service. I searched for some popular memes. Each had alt-text baked in.

Take a look and tell me if you think that the embedded text conveys the sentiment of the image? If you couldn't see the animation, would you understand what was going on from that alt?

2025-09-07, 21:11 12 boosts 22 favorites

For more information on writing good alt text, see Harvard's Digital Accessibility​ blog and Design102's guide.