Captions are part of the image decision
You already know if the image is decorative
Most images on small sites fall into one of two buckets: they illustrate something specific that words can't convey alone, or they're there because a page "needs" an image. If you find yourself writing a caption that just describes what's visible—"A laptop on a desk"—the image is decorative. That's fine. But be honest about it.
Decorative images don't need captions. They need good alt text and a fast load time, and then you move on. The problem is when you treat illustrative images like decoration, or worse, when you add decoration and then try to retrofit meaning.
Captions clarify intent
A good caption tells the reader why the image is there. Not what it shows—that's the alt text's job—but what it contributes. "The dashboard after applying the new filter layout" is a caption. "Dashboard screenshot" is a filename you forgot to replace.
If you're writing about [CMS workflows](/category/production), a screenshot of a confusing admin panel makes sense. The caption might be: "The bulk edit screen before we separated publishing actions from metadata changes." Now the reader knows what they're looking at *and* why it matters to the paragraph above it.
When I can't write a caption that does that work, it's usually because the image isn't pulling its weight. I either find a better image or cut it entirely. This happens more often than I'd like to admit.
Captions expose weak image choices
Here's the test: if your caption is generic enough to work under three different images on the same page, you haven't thought through what the image is for. "Example of good navigation" could describe a dozen screenshots. "Navigation menu with visible section labels and a distinct active state" is specific. It implies you chose this image intentionally.
This is related to the [stop resizing images by eye](/posts/stop-resizing-images-by-eye) problem—if you're not sure why the image is there, you're also not sure how big it should be, where it should sit, or what it should show. The caption forces you to decide.
Write the caption first sometimes
If you know you need an image but haven't chosen one yet, write the caption. "The settings panel showing the three toggles we just discussed." Now you know what to screenshot. You're not hunting through your camera roll hoping something fits.
This works especially well for tutorial content or documentation. The caption describes what the reader should notice, and then you make sure the image shows exactly that. No extraneous UI, no distracting elements, no ambiguity about what you're pointing to.
Not every image gets a caption
Decorative images—hero images, section breaks, background textures—don't need them. If the image isn't referenced in the surrounding text and doesn't add specific information, leave the caption empty. The absence of a caption is itself a signal: this is here for pacing or visual interest, not instruction.
But if you're explaining something, demonstrating a technique, or comparing options, the caption is part of the explanation. Skipping it is like [writing subheadings that don't subdivide](/posts/subheadings-that-actually-subdivide)—you're withholding structure that would help the reader.
Captions make images earn their kilobytes
Every image costs something: load time, visual weight, the reader's attention. A caption is a small additional cost that clarifies whether the image is worth it. If you can't write a useful caption, you probably can't justify the image.
I've started treating captions as a required field in my CMS for any image in body content. Not because every image objectively needs one, but because the act of writing—or consciously skipping—a caption makes me think harder about whether the image belongs on the page at all. That's a decision worth making deliberately.