Table Of Contents
Introduction
If you have ever searched for something online and clicked on an image result, you have already experienced the result of good image SEO. But behind every image that ranks well in Google, there is a small but powerful piece of code called alt text. So, what is alt text in SEO? Why does it matter? And how can you write it correctly to improve your website’s visibility?
This complete guide will answer all of these questions. Whether you are a blogger, small business owner, web designer, or just someone who wants to learn SEO, this article will walk you through everything you need to know about alt text – in simple, easy-to-understand language.
1. What Is Alt Text?
Alt text, short for alternative text, is a written description added to an image on a webpage. It is placed inside the HTML code of the image tag and tells people and search engines what the image is about.
Here is a basic example of what alt text looks like in HTML code:
| HTML Example: <img src=”red-apple.jpg” alt=”A fresh red apple on a wooden table”> |
In this example, the text inside the quotes – “A fresh red apple on a wooden table” – is the alt text. It describes the image so that even if the image does not load, the reader still knows what it was supposed to show.
Alt text is also sometimes called alt attribute, alt tag, or alternative description. While technically these terms have slight differences, in everyday usage they are often used interchangeably.
2. Why Does Alt Text Matter in SEO?
Now that you know what alt text is, the next question is: why is it so important for SEO? The answer lies in understanding how search engines and users interact with images on the web.
2.1 Search Engines Cannot See Images
Search engines like Google use bots – also called crawlers or spiders – to scan and understand web pages. These bots are excellent at reading text, but they cannot actually see or interpret images the way humans do.
When a search engine bot visits your page, it reads the alt text of your images to understand what those images contain. Without alt text, the bot simply skips the image, missing an opportunity to understand more about your content. With descriptive alt text, the bot gains a clear picture of what the image represents, which helps it better understand your whole page.
2.2 Alt Text Improves Image Search Rankings
Google Images is one of the largest search engines in the world. Millions of users search for images every single day. If your images have well-written alt text, they stand a much better chance of appearing in Google Images results – which can drive extra organic traffic to your website.
For example, if you run a recipe blog and have a photo of a chocolate cake, writing a clear alt text like “Homemade chocolate fudge cake with frosting” makes it far more likely that your image will appear when someone searches for chocolate cake recipes or images.
2.3 Alt Text Supports Website Accessibility
Accessibility is not just a moral responsibility – it also has SEO benefits. Alt text is used by screen readers, which are software tools that read webpage content out loud for visually impaired users. When a screen reader encounters an image with good alt text, it reads that description aloud, helping the user understand what the image contains.
Google and other search engines reward websites that are accessible and user-friendly. By writing good alt text, you are making your site more inclusive – and indirectly improving your SEO performance.
2.4 Alt Text Serves as a Fallback When Images Fail to Load
Sometimes images do not load properly – due to slow internet, broken image links, or browser issues. In such cases, the alt text is displayed in place of the image. This ensures that your page still communicates its message clearly, even when the visual element is missing.
3. How Does Alt Text Affect SEO Rankings?
Alt text is one of many signals that search engines use to understand and rank your content. Here is a closer look at how it directly influences your SEO performance:
3.1 Keyword Relevance
When you include relevant keywords in your alt text, you help search engines connect your image – and your page – to specific search terms. For example, if you are selling running shoes and you include alt text like “Blue lightweight running shoes for men”, this tells Google that your page is relevant to searches for running shoes.
| ⚠️ Warning: Important: Always write alt text that naturally describes the image first. Adding keywords should be secondary and should never force unnatural language. Keyword stuffing in alt text can actually harm your rankings. |
3.2 Page Relevance and Context
Search engines look at all the content on a page to understand its topic. Alt text contributes to this understanding. If your page is about healthy eating and your images have alt text like “Bowl of mixed green salad with cucumber and tomatoes”, it reinforces the topic of your page, signaling to Google that your content is genuinely about healthy food.
3.3 Better User Engagement
When your images appear in Google Image search results and are clicked on by users, it signals to Google that your content is valuable and relevant. Good alt text increases the chances of your images appearing in those results, which leads to more clicks, more traffic, and ultimately a positive signal to search engine algorithms.
4. How to Write Good Alt Text: Best Practices
Writing effective alt text is a skill that takes a little practice. Here are the best practices you should follow to get the most out of your image descriptions:
4.1 Be Specific and Descriptive
The most important rule of writing alt text is to be accurate and specific. Your alt text should clearly describe what is in the image. Think about what someone would need to know if they could not see the image at all.
For example:
| ❌ Bad: alt=”dog” ✅ Good: alt=”Golden retriever puppy playing with a tennis ball on green grass” |
The bad example is too vague. The good example tells you the breed of the dog, what it is doing, and where it is – giving a complete picture without actually seeing the image.
4.2 Keep It Concise
While being descriptive is important, you should also keep your alt text concise. Most SEO experts recommend keeping alt text under 125 characters, as screen readers often cut off at this length. You do not need to write a full sentence – a clear phrase is often enough.
4.3 Include Your Target Keyword Naturally
If your target keyword fits naturally in the alt text, include it. But remember – the primary goal is to describe the image. Do not force a keyword in if it does not make sense.
For example, if your keyword is “organic green tea”, and your image shows a cup of green tea:
| ❌ Forced: alt=”organic green tea buy organic green tea online” ✅ Natural: alt=”Hot cup of organic green tea in a ceramic mug” |
4.4 Do Not Start With ‘Image of’ or ‘Picture of’
Search engines and screen readers already know they are reading an image description. Starting with phrases like “Image of…” or “Photo of…” is redundant and wastes valuable character space. Just describe what is in the image directly.
4.5 Do Not Stuff Keywords
Keyword stuffing means overloading your alt text with multiple keywords in an unnatural way. This is a common mistake and can lead to a Google penalty. Search engines are smart enough to detect this practice, and it can hurt your rankings rather than help them.
4.6 Use Empty Alt Text for Decorative Images
Not every image on your page needs descriptive alt text. If an image is purely decorative – like a background pattern, a horizontal divider line, or a generic stock photo used only for visual design purposes – you should use empty alt text (i.e., alt=””). This tells screen readers and search engines to skip the image entirely.
| 📌 Note: For decorative images: <img src=”divider.png” alt=””> |
4.7 Think About the User First
Always write alt text with a human reader in mind. Ask yourself: if someone could not see this image, what would they need to know? Writing alt text that genuinely helps users will naturally also help search engines.
5. Common Types of Images and How to Write Alt Text for Them
Different types of images need slightly different approaches when writing alt text. Here is a breakdown by image type:
5.1 Product Images
For product photos on e-commerce sites, include the product name, key features, color, and any other relevant details.
| ✅ Example: Example: alt=”Black leather wallet for men with multiple card slots and zipper pocket” |
5.2 Infographics
Infographics contain a lot of information. Your alt text should summarize the key message or topic of the infographic, since you cannot describe every detail in 125 characters.
| ✅ Example: Example: alt=”Infographic showing the top 10 benefits of drinking water daily” |
5.3 Graphs and Charts
For graphs and charts, describe what the data shows or the main conclusion that can be drawn from the chart.
| ✅ Example: Example: alt=”Bar chart comparing monthly website traffic from January to June 2024, showing a 40% increase in June” |
5.4 People and Portraits
When writing alt text for images of people, include relevant context such as their role, what they are doing, or the setting – but only if it is relevant to the page content.
| ✅ Example: Example: alt=”Female doctor in white coat examining patient in a hospital room” |
5.5 Logos
For logo images, include the company or brand name in the alt text.
| ✅ Example: Example: alt=”Anthropic company logo” |
5.6 Screenshots
For screenshots of software, apps, or websites, describe what is being shown and why it is relevant to the surrounding content.
| ✅ Example: Example: alt=”Screenshot of Google Search Console showing a drop in organic traffic for June 2024″ |
6. Alt Text vs. Image Title vs. Image Caption: What Is the Difference?
Many people confuse alt text with image titles and captions. Let us clear this up:
| Attribute | What It Is | SEO Importance |
| Alt Text | HTML attribute describing the image content. Invisible to most users. | High – read by search engines and screen readers |
| Image Title | Optional HTML attribute shown as a tooltip on hover. Not always read by screen readers. | Low – minimal SEO value |
| Image Caption | Visible text placed below the image on the webpage. | Moderate – visible to users and search engines as page content |
In short, alt text carries the most direct SEO weight of the three. While captions and titles can also contribute to user experience and page context, alt text is the most critical for image SEO.
7. How to Add Alt Text in Popular Platforms
Adding alt text is straightforward across most popular website platforms. Here is a quick guide for the most common ones:
7.1 WordPress
WordPress makes it very easy to add alt text to your images:
- When uploading an image via the Media Library, you will see an
- Alt Text field on the right side. Simply type your alt text there.
- If you are adding an image to a page or post using the Block Editor (Gutenberg), click on the image block. In the settings panel on the right, you will find the
- Alt text field under Image Settings.
7.2 Shopify
In Shopify, you can add alt text to product images by:
- Going to your Products section and opening a product.
- Clicking on an image, then selecting the option to edit the image.
- Entering your alt text in the provided field and saving.
7.3 Squarespace
In Squarespace, click on any image to open its settings. Under the Design or Content tab, you will find a field to enter alt text. The exact location can vary slightly depending on the version of Squarespace you are using.
7.4 Wix
In Wix, click on an image in the editor, then click Settings. You will find an Alt Text field where you can type your description.
7.5 Raw HTML
If you are editing raw HTML, simply add the alt attribute inside your <img> tag, like this:
| HTML: <img src=”sunset-beach.jpg” alt=”Sunset over a calm ocean beach with orange and pink sky”> |
8. Alt Text and Accessibility: The Bigger Picture
We briefly touched on accessibility earlier, but it deserves a deeper look because accessibility and SEO are more connected than most people realize.
8.1 What Is Web Accessibility?
Web accessibility means designing and building websites so that people with disabilities can use them effectively. This includes people who are blind or have low vision, people who are deaf or hard of hearing, and people with motor or cognitive disabilities.
8.2 How Alt Text Helps Visually Impaired Users
For people who are blind or have low vision, screen readers are essential tools. A screen reader scans the HTML of a webpage and reads the content out loud. When it reaches an image, it reads the alt text associated with that image.
Without alt text, a screen reader might simply say “image” or skip over it entirely – leaving the user confused about what content they might be missing. Good alt text transforms an inaccessible image into a meaningful piece of content.
8.3 Legal and Compliance Aspects
In many countries, websites – especially those of government bodies, educational institutions, and large businesses – are legally required to meet accessibility standards such as the Web Content Accessibility Guidelines (WCAG). Providing proper alt text is one of the key requirements of WCAG. Non-compliance can sometimes lead to legal action.
8.4 Google’s Stance on Accessibility
Google has consistently stated that it values accessible, user-friendly websites. While accessibility is not a direct ranking factor in the way that backlinks or page speed are, accessible sites tend to have better engagement metrics – lower bounce rates, longer dwell times, and more pages visited. These signals positively influence SEO.
9. Common Alt Text Mistakes to Avoid
Even experienced website owners make mistakes with alt text. Here are the most common ones and how to avoid them:
9.1 Leaving Alt Text Blank (Unintentionally)
One of the most common mistakes is simply forgetting to add alt text at all. When you upload images, it is easy to skip the alt text field, especially if you are in a hurry. Make it a habit to always fill in the alt text field whenever you add an image to your site.
9.2 Using the File Name as Alt Text
Some content management systems automatically use the file name of the image as the alt text. If your file names are something like “IMG_20230415_001.jpg”, this becomes very unhelpful alt text. Always write a meaningful description manually, and also consider renaming your image files to something descriptive before uploading them.
9.3 Writing Alt Text That Is Too Vague
Alt text like “beautiful image” or “photo” provides zero useful information. Be specific about what the image actually shows.
9.4 Writing Alt Text That Is Too Long
At the other extreme, some people write alt text that is too long – almost like a paragraph. This is also ineffective. Keep your descriptions focused and concise, covering only the most important details.
9.5 Repeating the Same Alt Text for Multiple Images
If you have multiple images on a page and they all share the same alt text, search engines may see this as lazy or duplicate content. Each image should have its own unique description that accurately reflects what it shows.
9.6 Using Alt Text for Images That Should Have Empty Alt Text
Remember: decorative images should have empty alt text (alt=””). Adding unnecessary descriptions for decorative visuals can clutter up the accessibility experience for screen reader users and dilute the SEO value of your genuine alt text.
10. Advanced Alt Text Strategies for Better SEO
Once you have the basics down, you can take your alt text strategy to the next level with these more advanced techniques:
10.1 Align Alt Text with Your Page’s Overall SEO Strategy
The images on a page should complement the page’s content and keyword strategy. Before writing alt text, review the target keywords for the page and think about how your images relate to those keywords. Your alt text can then naturally incorporate those keywords in a way that genuinely describes the image.
10.2 Use Long-Tail Keywords in Alt Text
Long-tail keywords are more specific keyword phrases, like “best yoga poses for lower back pain” instead of just “yoga”. Images are a great opportunity to target long-tail keywords, because image search queries tend to be more specific and descriptive.
10.3 Conduct an Alt Text Audit
If your website has been live for a while, chances are many of your images have missing or poor alt text. Conducting an alt text audit means reviewing all your images and updating their alt text according to best practices.
You can do this manually for smaller sites, or use SEO tools like Screaming Frog, Ahrefs, or SEMrush to crawl your site and identify images with missing or duplicate alt text.
10.4 Combine Alt Text with Other Image SEO Practices
Alt text is just one part of image SEO. For the best results, combine good alt text with these other image optimization practices:
- Use descriptive file names: Name your image files something relevant (e.g., red-running-shoes.jpg instead of img001.jpg).
- Compress your images: Large image files slow down your page. Use tools like TinyPNG or WebP format to reduce file size without losing quality.
- Use structured data: For product or recipe images, use schema markup to give search engines even more context.
- Create an image sitemap: An image sitemap helps Google discover and index all the images on your site.
11. Does Google Really Read Alt Text?
Yes – Google has publicly confirmed that it uses alt text to understand images. In its own documentation, Google explains that it reads alt text as one of the primary methods of understanding what an image depicts.
However, Google has also become increasingly sophisticated. It now uses machine learning and computer vision to analyze images independently. This means that even if you have no alt text, Google may still be able to understand the basic content of an image.
But here is the key point: Google’s ability to visually understand images does not replace the value of alt text. Alt text provides precise, keyword-rich context that visual recognition alone cannot reliably deliver. It is still very much a best practice for image SEO.
12. Quick Reference: Alt Text Do’s and Don’ts
| ✅ DO | ❌ DON’T |
| Describe the image accurately | Leave alt text blank |
| Be specific and concise (under 125 chars) | Write vague descriptions like ‘image’ |
| Include target keywords naturally | Keyword stuff or spam keywords |
| Use empty alt for decorative images | Add alt text to purely decorative images |
| Think about screen reader users | Start with ‘Image of’ or ‘Photo of’ |
| Make each image’s alt text unique | Use the same alt text for multiple images |
| Keep the context of the page in mind | Write alt text that ignores page content |
13. Real-World Example: Alt Text in Action
Let us walk through a practical, real-world example to see how alt text works in context.
Imagine you run a travel blog and you are writing an article about visiting the Eiffel Tower in Paris. You include a photograph taken at sunset. Here is how different alt text choices affect your SEO and accessibility:
| Alt Text Version | Alt Text Used | Result |
| No Alt Text | (blank) | Google cannot understand image. Screen readers skip it. |
| Too Vague | tower | Very little SEO value. No helpful context. |
| Better | Eiffel Tower at sunset | Decent SEO value. Some keyword relevance. |
| Best | Eiffel Tower illuminated at sunset in Paris, France | Strong SEO value. Descriptive, accurate, keyword-rich. |
Conclusion
So, what is alt text in SEO? In summary, alt text is a brief, descriptive piece of text attached to an image in HTML. It serves three essential purposes: it helps search engines understand your images, it improves your rankings in image search results, and it makes your website accessible to users who rely on screen readers.
Writing good alt text is one of the simplest and most cost-effective things you can do to improve your website’s SEO. It requires no technical skills, no expensive tools, and very little time – but it can make a significant difference in how Google views your content and how many visitors find your site.
The core principles are straightforward: be descriptive, be concise, include relevant keywords naturally, and always think about the human reader first. Follow these guidelines consistently across your entire website, and you will be well on your way to stronger image SEO and a more accessible web experience for everyone.
| 💡 Key Takeaway: Alt text is small in size but big in impact. Never upload an image without giving it thoughtful, descriptive alt text – your SEO (and your users) will thank you for it. |
About the Author
Jay Patel is the Founder of XSquareSEO, a full-service SEO agency with experience in on-page SEO, eCommerce SEO, link building, technical SEO, SaaS SEO, and local SEO. For more information, feel free to contact us.
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