Alt text (the alt attribute) is a short text description of an image. Screen readers read it to people who cannot see the image, and it is shown if the image fails to load. Search engines also use it to understand what an image is about.
Here are simple rules, examples, and the common mistakes to avoid.
Key Takeaway: Write for a person first. If you describe the image clearly and usefully, the SEO benefit follows without keyword stuffing.
Seven Rules for Good Alt Text
- Describe what matters. Say what the image shows in the context of the page.
- Be concise. One short sentence is usually enough, often under about 125 characters.
- Skip “image of”. Screen readers already announce it as an image.
- Include text that is in the image. If a graphic contains words, write them.
- Use keywords naturally. Only when they genuinely describe the image.
- Describe the action for linked images. A logo link should say where it goes, such as “TinyPNG Now home”.
- Leave decorative images empty. Use
alt=""so screen readers skip them.
Good vs Bad Examples
| Bad | Better |
|---|---|
alt="image" | alt="Golden retriever catching a frisbee in a park" |
alt="shoes shoes buy shoes cheap" | alt="White leather running shoes, side view" |
alt="IMG_2043.jpg" | alt="Chart showing website load time dropping from 4s to 2s" |
Alt Text vs Title vs File Name
The alt text describes the image for accessibility and search. The title attribute is optional extra info that appears as a tooltip and is not a substitute. The file name, for example red-bicycle.jpg, also gives context. Use all three sensibly, as covered in our image SEO guide.
Add Alt Text Without Slowing Your Pages
Alt text does not affect file size, but images do. Resize and compress them too, as explained in images and PageSpeed and optimizing images for WordPress. Run each image through the compressor before you upload.
Quick check: Read your alt text aloud without seeing the image. If someone could still understand the page, it is doing its job.
Frequently Asked Questions
What is alt text?
Alt text is the alt attribute on an image tag: a short description read by screen readers and used by search engines, and shown if the image cannot load.
How long should alt text be?
Keep it brief, usually one short sentence. Under about 125 characters is a common rule of thumb.
Does alt text help SEO?
Yes. Descriptive alt text helps search engines understand an image and can support image search, but stuffing keywords can hurt.
When should alt text be empty?
For purely decorative images that add no information. Use alt="" so screen readers skip them.
Should I write 'image of' in alt text?
No. Screen readers already identify it as an image, so start directly with the description.
Summary: Describe what matters briefly, skip filler and keyword stuffing, and leave decorative images empty. Pair good alt text with compressed images using the free TinyPNG Now compressor.