What Is Alt Text? A Simple Guide for SEO & Accessibility

Alt text is a short written description of an image on a web page. It tells people and search engines what the picture shows, even when the picture itself can’t be seen. If you run a website, add a blog, or upload photos to WordPress, alt text is one of the simplest things you can get right — and one of the easiest to forget.

In this guide, you’ll learn what alt text is, why it matters for accessibility and SEO, and how to write it well — with real examples, the mistakes most people make, and how to add it in WordPress.

What Is Alt Text?

Alt text, short for alternative text, is a short description you attach to an image in your page’s HTML code. It sits inside the image tag, in an attribute called alt. Here’s what it looks like:

<img src="golden-retriever.jpg" alt="A golden retriever puppy sleeping on a grey dog bed">

The text inside the quotes is the alt text. Most visitors never see it. It shows up when a screen reader reads the page out loud, when the image fails to load, and when a search engine reads the page to work out what the image is about.

People use a few terms for the same idea:

• Alt text: the actual description you write, like “A golden retriever puppy sleeping on a grey dog bed.”
• Alt attribute: the technical name for the alt="" part of the HTML image tag.
• Alt tag: a common but slightly wrong name. Alt is an attribute of the image tag, not a tag on its own. Most people will still know what you mean if you say “alt tag.”

Why Alt Text Matters

Alt text does three jobs at once. It makes your site usable for people who can’t see your images, it helps your images show up in search results, and it covers you when an image breaks.

1. Accessibility: Screen Readers Read It Aloud

This is the main reason alt text exists. People who are blind or have low vision use screen readers — software like JAWS, NVDA, and VoiceOver — that reads a web page out loud. A screen reader can’t look at a photo and work out what’s in it. It can only read text.

When a screen reader reaches an image, it reads the alt text. So instead of hearing “image” and moving on with no idea what was there, the person hears “A golden retriever puppy sleeping on a grey dog bed” and gets the same information a sighted visitor gets from looking at the photo.

2. SEO: Search Engines Use It to Understand Images

Search engines can’t see images the way people do. They read the text around an image — the file name, the caption, the nearby paragraphs, and the alt text — to work out what the picture shows.

Clear, honest alt text helps your images appear in Google Images results, which can bring extra visitors to your site. Google’s own image SEO guide calls alt text the most important attribute for giving an image more context, and warns against stuffing it with keywords.

3. It Shows Up When an Image Fails to Load

Sometimes an image doesn’t load — a slow connection, a broken file path, or a reader who has turned images off to save data. When that happens, the browser shows the alt text in place of the picture. Your reader still knows what was supposed to be there, instead of staring at a blank box or a broken-image icon.

How to Write Good Alt Text

Writing good alt text is a small skill, and it gets easier with practice. Follow these rules and you’ll be ahead of most websites.

Be specific, not vague. Say what the image actually shows. “A dog” tells the reader almost nothing. “A senior golden retriever sleeping on a grey dog bed” paints the picture.

Keep it short. Aim for one or two sentences, around 125 characters or less. Screen readers can cut off longer text. If an image needs a long explanation — a chart or an infographic — put the full explanation in the text near the image and keep the alt text to a short summary.

Describe the meaning, not just the looks. Ask yourself why the image is on the page. A chart is there to share numbers, so the alt text should share the main finding, not just say “a bar chart.”

Don’t start with “image of” or “picture of.” Screen readers already announce that it’s an image, so those words just waste the listener’s time. Get straight to the description.

Include text that’s inside the image. If the image has words in it — a sign, a quote graphic, an infographic — those words belong in the alt text, because a screen reader user can’t read them otherwise. Use keywords only if they fit naturally. If your page is about organic coffee and the photo shows coffee beans, “Freshly roasted organic coffee beans spilling from a burlap sack” is fine. But never cram a list of keywords into the alt text. Google treats that as spam, and it sounds awful when read aloud.

Good and Bad Alt Text Examples

Here are a few side-by-side examples so you can see the difference:

• Bad: alt="dog"
  Good: alt="Senior golden retriever sleeping on a grey dog bed"
• Bad: alt="IMG_4829.jpg"
  Good: alt="Woman holding a cup of coffee at a cafe table by the window"
• Bad: alt="image of a chart showing sales"
  Good: alt="Bar chart showing online sales rising from $10,000 in January to $25,000 in June"
• Bad: alt="best running shoes cheap running shoes buy running shoes online"
  Good: alt="Blue running shoes with white soles on a track"

Alt Text vs Title and Caption: What’s the Difference?

Alt text, image titles, and captions are three different things. Here’s the short version:

• Alt text describes the image for screen readers and search engines. Visitors don’t normally see it. It’s the one that matters most.
• Caption is visible text shown under or next to the image. It adds context or a comment that all readers can see, like a photo credit or a short note about what’s happening in the picture.
• Title is extra information that may show as a small tooltip when someone hovers over the image. It’s optional, and it’s not a replacement for alt text. Most of the time you can leave the title blank.

A good rule: if the information matters, put it in the alt text or in the caption — not only in the title, where most people will never find it.

Alt Text for Decorative Images: When to Leave It Empty

Not every image needs alt text. Some images are purely decorative — a background pattern, a fancy divider line, or a stock photo that adds nothing the text doesn’t already say. For those, the right move is an empty alt attribute:

<img src="divider.png" alt="">

The empty quotes tell the screen reader to skip the image completely. That’s a kindness to the listener: hearing “decorative swirl” three times on one page helps nobody.

Use this simple test: if you removed the image and the page would lose no information, leave the alt text empty. If removing it would take something away, write a description.

How to Add Alt Text in WordPress

WordPress makes this easy. You don’t need to touch any code.

1. In the post or page editor, click the image to select it.
2. Look for the Alternative text field in the settings panel on the right. (In older versions of WordPress, it’s in the image settings in the sidebar.)
3. Type a short, clear description of the image.
4. If the image is decorative, leave the field blank — WordPress will output an empty alt attribute for you.

One more habit worth building: write the alt text at the same time you upload the image, not later. A library full of images with blank alt fields is a chore to fix, and most people never get around to it.

Common Alt Text Mistakes to Avoid

• Leaving alt text blank on important images. This is the most common mistake. If the image carries information, describe it.
• Using the file name as alt text. “IMG_4829.jpg” or “screenshot-2026-11-10” tells nobody anything. Replace it with a real description.
• Writing “image of” or “picture of.” Screen readers already say it’s an image. Skip those words.
• Stuffing keywords. A string of search terms is not a description. It reads badly for screen reader users and can hurt your SEO instead of helping it.
• Repeating the caption word for word. If the caption already says what’s in the photo, the alt text doesn’t need to say the same thing again.
• Writing a novel. Alt text is a short description, not a full article. If the image needs a long explanation, put that in the body text near the image.

Frequently Asked Questions

Should I include keywords in alt text?

Yes, but only when they fit naturally into an honest description of the image. Alt text should serve people first and search engines second. If the keyword describes what’s actually in the picture, include it. If you have to force it in, leave it out.

How long should alt text be?

Most good alt text is one or two sentences, usually under 125 characters. That’s long enough to describe the image and short enough that a screen reader won’t cut it off. Charts and infographics are the exception — give the key takeaway in the alt text and put the full details in the nearby text.

Do all images need alt text?

No. Images that carry meaning need alt text. Purely decorative images — borders, spacers, background patterns — should have an empty alt attribute (alt="") so screen readers skip them.

What happens if I leave alt text blank?

For a meaningful image, a screen reader user gets no information about it, and search engines get no clue about what the image shows. You also miss a small SEO chance. For a decorative image, a blank alt is exactly right.

Can I use AI to write alt text?

Some tools can draft alt text for you, and that can help with a large photo library. But always read and fix what the tool writes before you publish it. Automated descriptions often miss the point of the image or get details wrong, and only you know why you chose that picture for that page. For more on writing it well, Microsoft’s guide to effective alt text is a solid reference.

Alt text takes less than a minute per image, and it makes your site better for real people and easier for search engines to understand. Start with the images on your most-visited pages, then work through the rest a few at a time.