Alt text describes the image, not the metaphor
I used to write alt text like this: "Success concept illustration" or "Teamwork and collaboration imagery." It felt efficient. The image showed abstract shapes suggesting growth, so I named the concept.
That's backwards.
Alt text exists for people who can't see the image. They need to know what's in the picture, not what marketing idea it represents. A screen reader user doesn't benefit from "innovation visual" when the actual image shows three overlapping circles in blue, green, and orange.
Describe the literal content
Start with what you actually see. If it's a photo of a laptop on a wooden desk with a coffee mug in the corner, say that. If it's a diagram with five labeled boxes connected by arrows, describe the boxes and their labels.
Your alt text should answer: what would I tell someone over the phone if they asked what's in this image?
For decorative images that don't add information — background textures, ornamental dividers, aesthetic flourishes — use empty alt text: alt="". That tells screen readers to skip it entirely, which is honest. Not every image carries meaning.
Context lives in the surrounding copy
The metaphor or concept the image represents belongs in your body copy, your caption, or your heading. When you write captions as you add images, you have a natural place to explain why the image matters.
Alt text handles a different job: making the image's content accessible. The caption or surrounding paragraph connects that content to your point.
If you've written "Leadership growth concept" as alt text, ask yourself: could I describe this image to someone without using the word 'concept'? That's your alt text. The concept explanation goes in the caption.
Avoid redundant phrasing
Don't start with "Image of" or "Picture showing" — screen readers already announce it's an image. Just describe what's there.
Same with "screenshot of." If you're showing a software interface, describe what's visible in that interface: "Dashboard with three metric cards and a line graph below." The fact that it's a screenshot is usually obvious from context.
Length follows complexity
Simple images get short alt text. A logo might just be the company name. A decorative icon might be empty alt.
Complex images — charts, diagrams, detailed photos — need more description. If the image contains data someone needs to understand your point, describe that data. A bar chart showing monthly revenue might need: "Bar chart: January $45k, February $62k, March $58k, April $71k."
If the image is too complex for alt text to cover fully, describe the key visible elements in alt text and provide a longer text description nearby in your content.
Test by hiding the image
Temporarily hide the image in your browser and read your alt text in context with the surrounding copy. Does the page still make sense? Can you follow the point you're making?
If your alt text says "growth" but your paragraph doesn't mention what's growing or why, you've probably written metaphor alt text. Flip it: describe what's literally in the image, then make sure your surrounding copy carries the conceptual weight.
Alt text isn't a keyword field. It's not a place to reinforce your SEO themes. It's a description of visible content for people who can't see it. Write it that way.