Describe the image’s purpose and meaning
Keep it concise and specific
Include essential details only
Mention text shown in the image if relevant
Avoid phrases like “image of” or “picture of”
Do not repeat nearby caption or surrounding text
Focus on what a sighted user would need to know
Omit decorative details that do not add value
For functional images, describe the action or destination
For complex images, summarize the key takeaway
Use proper names, labels, and context when important
Match the alt text to the image’s role on the page
Leave alt text empty for purely decorative images when appropriate