Images are one of the most consistently under-optimized parts of a website. They're often the heaviest thing on a page, load-time-wise, and the least described, content-wise — a missed opportunity twice over, since images can drive real traffic through image search and directly affect how fast the rest of the page loads.
What Actually Matters for Image SEO
Alt text describes an image for anyone who can't see it — screen reader users, and search engines, which can't "see" an image the way a person can. Good alt text is a genuine description, not a keyword dump: "golden retriever puppy playing in autumn leaves," not "dog puppy pet golden retriever cute animal."
File names should describe the image before it's ever uploaded — red-leather-office-chair.jpg tells a search engine far more than IMG_4821.jpg ever will.
File size affects page speed directly, and page speed affects both rankings and how many visitors stick around long enough to see the image at all. A single unoptimized hero image can outweigh every other speed optimization on the page combined.
Context — the text surrounding an image — also plays a role. An image sitting inside a relevant paragraph gets more topical credit than the same image floating in an unrelated section.
A Simple Framework
- Rename image files descriptively before uploading, using hyphens between words
- Write alt text that genuinely describes the image, working the topic in naturally rather than stuffing keywords
- Compress and properly size every image before it goes live — no image should be larger than it needs to be at its actual display size
- Use a descriptive caption or surrounding text where it adds genuine value, not as another keyword opportunity
> Tip: Write alt text as if describing the image to someone on the phone who can't see it. If it would sound strange said out loud, it's probably over-optimized.
Common Mistakes
- Leaving alt text blank entirely, especially on meaningful, content-relevant images
- Stuffing alt text with keywords instead of a genuine description
- Uploading full-resolution camera images without compressing or resizing them first
- Using generic file names like
image1.jpgacross dozens of images
Checking a page's page size is a fast way to see whether images are quietly weighing a page down, and pulling the source code confirms alt text is actually present and hasn't been dropped during a redesign or CMS migration.
Images are often the single heaviest element on a page and the most overlooked from an SEO standpoint — a few minutes of attention per image adds up to a meaningfully faster, more discoverable site.