Alt Text for Images: What It Is, Why It Matters, and How to Use It Correctly

Images are a huge part of the modern web. They make websites more interesting, help explain complicated ideas, show products, establish a brand visually and, in many cases, communicate information that would be difficult to convey with words alone. But there is a problem with images that is easy to overlook. A person looking at a screen can immediately understand what a photograph, diagram or graphic is showing, while someone using a screen reader may have no idea what that image contains unless the website provides a text alternative. Search engines have the same basic challenge. They have become remarkably good at interpreting images, but they still rely on the surrounding page content and other signals to understand what an image represents and why it matters.

That is where alt text comes in. Alt text, short for alternative text, is a small piece of HTML associated with an image that describes the image’s meaning or purpose. It is one of those seemingly minor pieces of website content that is easy to ignore when building a site, but it sits at the intersection of accessibility, usability, content and search. And like a lot of things in SEO, alt text is frequently misunderstood. It is not a place to dump keywords, it is not a secret ranking trick, and it is not necessarily a description of every tiny visual detail in a photograph. The better question is much simpler: If someone couldn’t see this image, what would they need to know about it? That question will get you much closer to useful alt text than trying to figure out how many keywords you can squeeze into an image description.

What Exactly Is Alt Text?

Alt text is the text contained in an image’s alt attribute. A basic image might look something like this in HTML:

<img src="denver-web-design.jpg" alt="Web designer reviewing a website layout on a computer in Denver">

The visitor normally doesn’t see that sentence on the page. The image is displayed instead. The alternative text exists as another way of communicating the information or function represented by the image when the image itself cannot be effectively perceived or used. This distinction matters because alt text isn’t really about describing pictures for the sake of describing pictures. It is about providing an equivalent experience when the visual itself isn’t available. A photograph showing a finished building, for example, may need an explanation of what the photograph represents. A graphic functioning as a button may need to describe what clicking it does. A decorative background image may need no description at all.

The purpose of the image determines what its alternative should communicate. That is why there isn’t one universal formula for writing alt text. A photograph, logo, screenshot, chart, diagram, product photograph and navigation icon can all require completely different approaches even when they appear on the same website. Good alt text isn’t necessarily the text that describes the most things in the picture. It is the text that preserves the information or function that would otherwise be lost.

Alt Text Is Primarily About Accessibility

This is the part that sometimes gets lost when alt text is discussed primarily as an SEO technique. Alt text exists first and foremost to make images accessible. If your website contains an important image and that image has no useful alternative text, someone who cannot see the image may be missing information that sighted visitors receive automatically. Imagine a construction company’s website with a photograph showing a newly completed medical clinic. A sighted visitor can immediately understand what the photograph is showing. Someone using a screen reader may simply encounter an image without meaningful context. A useful alternative might be something like Completed medical clinic interior with reception desk and patient waiting area. The goal isn’t to write an essay about the photograph. The goal is to communicate the important information the image contributes to the page.

This is part of a much larger principle in good web design: a website shouldn’t be designed only for the person who happens to interact with it in the most convenient way. It should communicate its information clearly across different devices, situations and abilities. Accessibility isn’t a separate layer that gets bolted onto a website after the design is finished. It is part of how the website communicates in the first place. When you think about a website this way, alt text stops looking like another technical checkbox and starts looking like what it actually is — a way of making the information contained in a visual available to more people.

Not Every Image Needs Descriptive Alt Text

This is one of the most important things to understand about alt text, because the advice to “add alt text to every image” is technically simple but practically incomplete. Some images are there purely for decoration. Maybe you’ve added a background flourish between sections, a decorative graphic beside a heading, or a photograph simply to add visual atmosphere to an otherwise text-heavy article. If the image doesn’t contribute meaningful information, describing it to a screen reader user can actually make the experience worse. Instead of adding something like alt="Decorative blue abstract graphic", the appropriate HTML may simply be alt="". That tells assistive technology that the image is intentionally decorative and can be ignored. Importantly, alt="" is not the same thing as leaving the alt attribute out entirely. The empty value tells the browser and assistive technology that the image has been intentionally identified as decorative.

The goal isn’t to describe every image. The goal is to provide an appropriate alternative for images that communicate information or functionality. That sounds like a small distinction, but it changes how you should approach an entire website. If an SEO plugin tells you that 147 images are missing alt text, the correct response isn’t necessarily to sit down and invent 147 descriptions. First figure out which of those images actually need meaningful alternative text. A useful website isn’t one where every image has a sentence attached to it. A useful website is one where the important information is available and the decorative elements don’t get in the way.

Alt Text Isn’t the Same Thing as an Image Filename

Another common source of confusion is the relationship between alt text and the image filename. They’re different things. A filename might be denver-web-design-company.jpg, while the alt text might be Web designer reviewing a responsive website layout on a desktop monitor. The filename can provide useful context, but it isn’t a replacement for alt text. Likewise, changing an image filename doesn’t magically create accessible content.

I generally recommend giving images sensible filenames before uploading them rather than leaving everything named something like IMG_4827.jpg. A descriptive filename makes the media library easier to manage and can provide additional context about the asset. It is simply another small piece of good website organization. But don’t confuse that with the image’s alternative text. The filename identifies the file; the alt text provides an alternative to the visual content. They’re related, but they aren’t interchangeable.

Alt Text Isn’t the Same Thing as an Image Title

WordPress can make this more confusing because an image can have several different fields associated with it. You may encounter a filename, title, caption, description and alt text, all sitting around the same image. They serve different purposes. A caption is visible to visitors and can provide additional context. The filename identifies the actual file. The image title is metadata associated with the image. Alt text provides an alternative representation of the image when the visual itself isn’t available or isn’t being perceived.

This distinction becomes particularly important when you’re auditing an older website. A site may have perfectly good image titles while having poor alt text, or it may have carefully written captions while leaving the alternative text empty. One doesn’t automatically fix the other. If important information is being communicated through an image, make sure that information has an appropriate text alternative rather than assuming another image field takes care of it.

How Does Alt Text Affect SEO?

This is where the subject gets a little more interesting. Alt text can contribute to SEO because search engines use a variety of signals to understand images and the pages those images appear on. Properly described images can also provide additional context about a page and can help search engines understand what an image represents. But that doesn’t mean alt text is a magic ranking lever. Adding alt="Denver web design company" to every image on your website isn’t going to turn the website into the number-one result for Denver web design. In fact, doing that repeatedly can make the website worse.

The better way to think about alt text is that it helps search engines understand an image within the context of the page while simultaneously making the page more accessible. That’s a much more useful relationship. This is consistent with the broader approach I take to SEO. Search optimization works best when you’re helping a search engine understand something that is already useful and relevant to a real person. The optimization should reinforce the meaning of the page rather than manufacture meaning that isn’t there. If an article is about website performance and contains a screenshot of a PageSpeed report, an alt description explaining what the screenshot represents makes sense. If the same article has a decorative background image, forcing a keyword into the alt text doesn’t. Describe what is actually there.

Don’t Stuff Keywords Into Alt Text

This is probably the most common alt-text mistake I see. Someone learns that alt text can help search engines understand images and decides every image should contain the company’s target keyword. So instead of alt="Designer reviewing a website layout", they write something like alt="Denver web design Denver website design Denver SEO company Denver web development". That’s not useful. It’s awkward for humans, bad for accessibility and doesn’t accurately describe the image. The image isn’t suddenly about four different SEO keywords because you put those words into the alt attribute.

Good alt text should describe the image in the context in which it is being used. If the image genuinely depicts a Denver web designer reviewing a website project, then “Denver” may be appropriate. If the photograph was taken in Denver but the location has absolutely nothing to do with the image’s purpose, adding Denver simply to target a local keyword isn’t particularly helpful. This is one of those situations where relevance beats optimization theater. The same principle applies throughout SEO. A page doesn’t become more authoritative because a keyword has been repeated another six times. Context, usefulness and relationships between pieces of information matter much more than mechanically inserting phrases wherever a field happens to exist.

That’s also why I wouldn’t treat alt text as an isolated SEO task. It belongs within the larger Denver SEO strategy of a website rather than being treated as a standalone ranking trick. The strongest local websites aren’t the ones that simply repeat a city name everywhere they can. They’re the ones that make it clear who they serve, where they operate, what they do and why the information they’re publishing is relevant.

When Should You Include a Location in Alt Text?

For local businesses, this comes up constantly. Let’s say you’re a Denver construction company and you’ve got a photograph of a medical clinic your company actually built in Colorado Springs. A reasonable alt description might be Medical clinic interior completed by a Colorado construction company in Colorado Springs. If the location is important to understanding the photograph, including it makes sense.

But imagine you have a generic stock photograph of someone sitting at a laptop. Calling it Denver web design company creating websites doesn’t make the image more relevant simply because your company happens to be in Denver. That’s backwards. Describe the image first, then consider whether location is genuinely part of the image’s meaning or context. Local SEO doesn’t improve because every photograph on your website has been turned into a location keyword container. If anything, that kind of approach makes the content feel less trustworthy because the description no longer reflects what the image actually represents.

What Makes Good Alt Text?

Good alt text is generally concise, specific and relevant. Consider a photograph of a person working on a website. alt="person" is technically a description, but it doesn’t tell us much. alt="Web designer reviewing a website layout on a computer" is considerably better. If the context actually requires it, alt="Web designer reviewing a responsive website layout on a desktop monitor" may be better still. But there is an important wrinkle here: the best version depends on the surrounding content.

If the paragraph immediately before the image already explains that a Denver web designer is reviewing a responsive website, repeating all of that information in the alt text may be unnecessary. Alt text should complement the page, not create an endless loop of repetition for someone using assistive technology. Think about what information the image contributes. That’s the part you want to preserve. In many cases, the strongest alt text is surprisingly simple because the surrounding page is already doing most of the explanatory work.

What About Screenshots?

Screenshots are increasingly common on websites, particularly in tutorials, software documentation and technical articles. They’re also an area where lazy alt text can become a problem. Suppose you’re writing an article about Google Search Console and include a screenshot showing the Performance report. Calling the image Google Search Console screenshot isn’t terrible, but it may not communicate much. If the important information is that the screenshot shows clicks, impressions, average position and search queries, the alternative text should communicate the relevant information.

For example: Google Search Console Performance report showing clicks, impressions, average position and search queries. The exact wording depends on what the screenshot is being used to demonstrate. This is particularly important for technical content because screenshots often aren’t decoration. They’re part of the explanation. If the reader can’t see the screenshot, the article should still make sense. That doesn’t necessarily mean cramming every visible detail into the alt attribute. Sometimes the better solution is to explain the important information in the surrounding text and use the screenshot as a visual reference. This is another example of why accessibility and good content strategy overlap.

What About Charts and Diagrams?

Charts, diagrams and infographics require a little more thought. A simple chart might be described reasonably well with concise alt text, particularly if the surrounding content explains the actual numbers. A complicated infographic containing several pieces of important information may require a much more complete text equivalent. For example, an alt attribute that says alt="SEO infographic" does very little if the infographic actually contains a process explaining how pages are discovered, indexed and ranked.

If the information in the graphic matters, that information needs to be available to someone who can’t see the graphic. Sometimes the best implementation is to provide a concise alt description and then explain the substantive information in normal HTML text below or beside the image. That approach has another advantage: everyone gets access to the information, not just people who can see the graphic. It’s generally better website content anyway.

What About Logos?

Logos are another interesting case. If the logo is simply identifying the company and functions as a link to the homepage, the alt text will often appropriately identify the organization: alt="Big Orange Planet". If the logo contains important words that aren’t otherwise represented on the page, those words may need to be included in the alternative text.

The important question is what the logo is doing. If it’s functioning as a link, the alternative should help communicate what that link represents. If it’s simply decorative branding next to text that already identifies the company, the appropriate treatment may be different. Again, context wins. There isn’t a universal requirement that every logo on every page needs exactly the same alt text.

What About Images That Contain Text?

This one has become increasingly important because websites still use graphics containing headlines, promotional copy, statistics and other text. Whenever possible, important text should exist as actual HTML text rather than being trapped inside an image. That’s better for accessibility, responsive design, translation, search engines and users in general.

If a graphic says Denver Web Design and that wording is important to understanding the image, the alternative should account for that information. But if the same phrase already appears directly beside the graphic as normal HTML text, repeating it unnecessarily may not add much value. This is one of the reasons I generally prefer actual HTML text over putting a headline inside a JPEG and calling it a day. The web is much more flexible when the content is actually content instead of being baked into a picture. It also reinforces a broader principle of professional web design: don’t use an image to solve a problem that HTML and CSS can solve better.

What About AI-Generated Images?

This is where the subject gets more interesting. We’re now in a world where websites can contain photographs, illustrations, AI-generated images, screenshots, diagrams and graphics produced by a mixture of human and automated tools. That doesn’t eliminate the need for alt text. If anything, it makes thoughtful alt text more important.

An AI image generator might know that it created “a modern office with a person working on a laptop,” but that doesn’t necessarily tell you what that image is doing on your particular page. The person publishing the page knows the context. That’s what matters. If an AI-generated image is simply decorative, it may need an empty alt attribute. If it illustrates a concept being discussed in the article, the alt text should explain the relevant concept. If it shows a specific process or piece of information, the alternative should communicate that information. The fact that an image was generated by AI isn’t particularly important to the visitor trying to understand the content. The meaning and purpose of the image are what matter.

This is actually part of a much larger change happening across web development. We’re increasingly using AI to produce pieces of websites, from images and copy to layouts and code. But producing an asset and understanding how that asset fits into a website are two different things. That’s a distinction I explored in how website design can impact search rankings. Automation can produce the thing. It doesn’t automatically understand why the thing belongs there.

Can AI Write Your Alt Text?

Sure. And sometimes it can do a pretty good job. Modern image-recognition systems can identify objects, people, settings and relationships in photographs that would have been difficult to describe automatically a few years ago. That can make large image libraries considerably easier to manage. But I’d still review the result.

The problem isn’t necessarily whether AI can identify what’s in the picture. The problem is whether it understands why the picture is on your page. An AI system might correctly tell you that a photograph contains a person sitting at a computer, but perhaps the photograph is being used in an article about website conversion rates, and what actually matters is that the image represents someone reviewing a website. Those are subtly different descriptions. Context still requires editorial judgment.

That’s true whether the alt text is written by you, a developer, an SEO plugin or an AI tool. The best use of AI here is as an assistant rather than an excuse to stop thinking about the content. This is becoming a recurring theme with AI and websites in general: tools can make production faster, but speed doesn’t remove the need for someone to understand what the finished website is actually trying to communicate.

Should Every Image on Your Website Have Alt Text?

No. Every meaningful image should have an appropriate alternative, but that doesn’t mean every image needs a descriptive phrase. Some images are decorative and should have an empty alt value. Some images may already be sufficiently described by nearby text. Some images are functional and need alt text describing their purpose. Some complex graphics require a more complete textual explanation.

The important distinction is between having something in the alt field and providing an appropriate alternative. Those aren’t necessarily the same thing. A website full of meaningless alt text isn’t necessarily more accessible than a website that correctly identifies decorative images and provides meaningful descriptions for informative ones.

This is also why I wouldn’t let an automated audit dictate your entire alt-text strategy. Tools are useful for finding potential problems, but they aren’t always capable of understanding whether an image is actually important to the person using the page. That’s the same reason I recommend looking beyond individual technical warnings when evaluating indexing and ranking issues. A technical signal is useful, but it needs to be interpreted in context.

What Should You Do With Older Websites?

This is where alt text becomes a practical website-maintenance issue. If you’ve got a website that’s been around for five, ten or fifteen years, there’s a good chance the image library is inconsistent. Some images may have excellent alt text. Some may have filenames like DSC00482.jpg. Some may have keywords stuffed into the field because an SEO consultant told someone to do that years ago. Some may have no alt attribute at all. And some may have perfectly reasonable empty alt values because they’re decorative.

I wouldn’t recommend blindly going through thousands of images and filling every empty field. That’s the wrong approach. Instead, start with the pages and images that actually matter. Look at your important service pages, major landing pages, high-traffic articles, product pages and other content that contributes meaningfully to the website. Then ask of each important image: Does this image communicate something? If it does, make sure the alternative communicates that information. If it doesn’t, don’t manufacture a description simply because an SEO audit tool gives you a warning.

This is one of those places where automated SEO reports can create more work than value. An audit might tell you that a page has an image without alt text. That’s useful information. It doesn’t automatically mean that image needs a keyword-rich description. You still need to understand the page. And if the website has larger technical problems, I’d deal with those in the proper order rather than spending weeks obsessing over image fields while ignoring the underlying site. Things like performance, crawlability, site structure, internal linking and content quality all play a much larger role in how a website performs overall. My guide to configuring WP Rocket for better website speed is one example of the kind of technical work that can have a much broader effect than a handful of missing alt attributes.

Alt Text Is One Small Part of a Much Bigger SEO Picture

This is probably the most important takeaway. Alt text matters, but it isn’t the thing that’s going to make or break your SEO strategy. A properly written alt attribute isn’t going to compensate for a poor website structure, weak content, slow performance, bad internal linking, poor search-intent alignment or a website that simply doesn’t answer the customer’s question.

SEO is cumulative. The strongest websites tend to get a lot of relatively small things right. The structure makes sense. The content is useful. The pages answer real questions. Internal links connect related subjects. Images are properly implemented. The website is accessible. The technical foundation is sound. The business information is consistent. The site gives both users and search engines enough context to understand what it is about. Alt text belongs in that larger picture. It is one piece of the foundation, and because it takes relatively little effort to do correctly, there isn’t much reason not to do it correctly.

This is also why I think it’s useful to stop separating “SEO” and “web design” quite so aggressively. They’re different disciplines, but they overlap constantly. The way a page is structured, the way information is presented, the way images are used, the way navigation works and the way content connects all influence how people experience a website and how search engines understand it. That’s ultimately why the work we do around Denver web design and Denver SEO can’t really be treated as two completely separate conversations. A good website has to do both jobs.

The Simplest Way to Think About Alt Text

Forget the SEO tricks for a minute. Forget the keyword research. Forget the plugins telling you that your image is missing a target phrase. Look at the image and ask: If the image disappeared, what information would the visitor lose? If the answer is “nothing,” the image may be decorative and an empty alt attribute may be appropriate. If the answer is “they’d lose some important information,” write a concise alternative that communicates that information. If the answer is “the image is a button or link,” describe what the button or link does. If the answer is “the image contains a complicated chart or diagram,” make sure the information contained in the graphic is available in text somewhere on the page.

That’s really the heart of good alt text. It’s not about writing for a search engine. It’s about making the information on your website available in more than one way. And that happens to be good for SEO, too. A website that communicates clearly to people is generally a better website for search engines to understand. That’s not because Google awards some magical number of points for writing the perfect alt attribute. It’s because a well-constructed website tends to make its meaning clearer across the entire system — content, structure, images, navigation, accessibility and technical implementation.

Alt text isn’t an SEO trick. It’s part of building a better website.

And that’s a much better reason to get it right.

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