Alt text is one of the smallest details in web design, and one of the easiest to overlook. It is the short written description attached to an image in your site’s HTML, and it quietly does a lot of work. It keeps your content usable when images fail to load, makes your site accessible to people using screen readers, and gives search engines a way to understand what your images show. Often called “alt tags,” these descriptions are a small but real part of how image alt text and SEO work together to support your search visibility.
This post explains what alt text is, why it matters, how to write it well, and the common mistakes to avoid. If you also want to think more broadly about the images themselves, see our guide on how to choose and use photos on your website.
Table of Contents
- Understanding Alt Text
- Why Alt Text Matters
- Putting Alt Text to Work
- Alt Text Best Practices
- Common Mistakes to Avoid
- FAQs About Alt Text
Understanding Alt Text
Alt text, or alternative text, is a concise description of an image embedded in your website’s HTML. It acts as a textual stand-in for the image, so if the picture does not load, the reader still understands what was meant to be there. It matters for accessibility and for SEO, because search engines cannot “see” images the way people do. They rely on these descriptions to understand what an image depicts.
Every page on your site benefits from good alt text. That includes your home page, service pages, blog posts, and landing pages. Alt text conveys your message when visuals fail and reinforces the relevance of your pages to search engines.
Why Alt Text Matters
1. Boosting Accessibility
Accessibility is a core part of good web design. Screen readers rely on alt text to describe images to people who cannot see them, so leaving it out can unintentionally exclude a meaningful part of your audience. Providing it is both an ethical practice and a step toward ADA-aligned accessibility.
2. Enhancing User Experience
Alt text also protects the experience when something goes wrong. If an image fails to load because of a slow connection or a browser setting, alt text fills the gap so visitors still understand the context instead of staring at an empty box. That small reassurance keeps people engaged and reading.
3. SEO Advantages
Search engines use text-based cues to index content, and alt text is one of them. Clear, relevant descriptions help Google understand your images and the page around them, which can support your rankings and help you appear in image search. For a local business, that extra visibility can bring in traffic that would otherwise never find you.
Putting Alt Text to Work
1. Writing Effective Alt Text
Good alt text is meaningful, concise, and specific. Describe what the image actually shows, and where it fits naturally, include a relevant keyword without stuffing. “Front porch of a colonial home in Huntington” tells a search engine far more than “house1.jpg.” The goal is an honest description that happens to reinforce the topic of the page.
2. How Alt Text Fits Into Your Broader SEO
Alt text is one piece of a much larger picture. It works alongside page speed, mobile responsiveness, metadata, header structure, and internal linking. None of these wins on its own, but together they shape how well a page performs. If you want a practical starting point, our quick tips to improve your site’s SEO cover several of these in one place.
3. Keeping Alt Text Up to Date
Alt text is not a set-and-forget task. As you swap images, add pages, or refresh content, the descriptions should keep pace so they stay accurate and relevant. A quick review whenever you update a page keeps everything consistent and search-friendly.
Alt Text Best Practices
- Be descriptive: clearly describe the image content without keyword stuffing.
- Keep it concise: aim for around 125 characters or fewer for screen reader compatibility.
- Include relevant keywords: work them in naturally, only where they fit.
- Avoid redundancy: skip phrases like “image of” or “picture of,” since screen readers already announce images.
- Use unique text: give every image its own description, especially on important pages.
Common Mistakes to Avoid
Even experienced designers slip up with alt text. Watch out for these:
- Leaving alt text empty or generic, like “image1.”
- Stuffing keywords unnaturally.
- Reusing the same description across many images.
- Forgetting to update alt text when images or content change.
FAQs About Alt Text
1. What is the main purpose of alt text?
Alt text provides a written description of an image so people using screen readers can understand it, and so search engines can interpret what the image shows.
2. Does every image need alt text?
Almost. Any image that carries meaning should have alt text. Purely decorative images can use empty alt text so screen readers skip them.
3. Can alt text improve my Google ranking?
It can help. Well-written alt text supports indexing and can improve visibility, especially in image search, though it works best as part of a broader SEO effort.
4. Should I include keywords in alt text?
Yes, but only where they fit naturally and describe the image. Forced keywords can read as spam and hurt more than they help.
5. How long should alt text be?
Keep it concise, generally around 125 characters, so screen readers can read it fully and the description stays clear.
Conclusion
Alt text is a small element with an outsized impact. It makes your site more accessible, protects the experience when images do not load, and gives search engines one more clear signal about your content. Adding thoughtful descriptions to your images is one of the simplest, highest-value habits you can build into your workflow, and it pays off across accessibility, user experience, and SEO alike.