Alt text (alternative text) is an HTML attribute that describes what an image shows. It lives inside the img tag as alt="description here". Screen readers use it to describe images to visually impaired users. Search engines use it to understand image content since they can’t see images the way humans do. When an image fails to load, the alt text displays in its place.
Alt Text vs. No Alt Text: What Google Sees
✕ No Alt Text
<img src=”doctor-exam.jpg”>
- Google has no context for the image
- Screen readers announce “image” with no description
- Image won’t rank in Google Image Search
- Accessibility violation
✓ With Alt Text
<img src=”doctor-exam.jpg” alt=”physician reviewing patient chart during exam”>
- Google understands the image content
- Screen readers describe what’s shown
- Eligible to appear in Image Search results
- Reinforces page topical relevance
How to Write Good Alt Text
1
Describe what’s actually in the image
Pretend you’re describing it to someone who can’t see it. Be specific about the subject and context.
✕ “image1.jpg”
✓ “cardiologist reviewing EKG results with patient”
2
Include a relevant keyword naturally — when it fits
If the page is about orthopedic surgery and the image shows a doctor, it’s appropriate to include “orthopedic surgeon” in the description. Don’t force it.
3
Keep it under 125 characters
Screen readers often truncate at 125 characters. Be concise and prioritize the most important description first.
4
Leave alt text empty for decorative images
Purely decorative images — dividers, background shapes, spacers — should use
alt="". This tells screen readers to skip the image rather than announcing it.✕
Don’t keyword-stuff alt text
Writing “best dermatologist skin care clinic dermatology specialist near me” as alt text is a spam signal to Google. It also fails users who rely on screen readers.
Alt text is one of several on-page optimization signals. For a complete picture of how images, headings, and content structure work together to drive rankings, see Direction’s overview of healthcare SEO.