Images can bring a surprising amount of search traffic, through Google Images, the image results inside normal searches, and Discover. They also affect how fast a page loads, which matters for ranking and for visitors. This checklist covers what actually makes a difference, in plain language.
1. Write useful alt text
Alt text (the alt attribute) describes an image for people using screen readers and for search engines. It is the single most important image SEO signal you control.
- Describe what is in the picture, in the context of the page: “Hand-woven Paithani saree in peacock green with gold zari border” is far better than “saree” or “IMG_2041”.
- Keep it to a sentence or so. Don't stuff it with keywords.
- Purely decorative images (dividers, background shapes) should have an empty
alt=""so screen readers skip them. - Don't start with “Image of…”; screen readers already announce it as an image.
2. Use descriptive file names
Google reads file names as a small hint. paithani-saree-peacock-green.jpg tells it more than DSC00341.jpg. Use lowercase words separated by hyphens, and rename files before you upload them; changing them later breaks old links.
3. Put images near relevant text
Search engines understand an image partly from the words around it: the heading above it, the caption and the paragraph next to it. An image placed next to text that explains it ranks better than the same image in a random gallery. Captions are read more than almost any other text on a page, so use them where they help.
4. Choose the right format and size
Heavy images slow the page, and slow pages perform worse in search and lose visitors. Use WebP or AVIF for photos (with a JPEG fallback if needed), SVG for logos and icons, and serve sizes that match how large the image is shown. Our guides on image formats, responsive images and auditing images for speed go into detail.
5. Use real <img> tags for important images
Google indexes images found in <img> elements (including srcset and <picture>). It does not index images used only as CSS backgrounds. If an image matters for search, such as a product photo or an infographic, put it in an <img> tag with alt text.
6. Lazy-load safely
Lazy loading is good for speed, but the real image address must be present in the HTML, not only added after a click or scroll. Native loading="lazy" is safe. Never lazy-load the first image visitors see. See our lazy loading guide.
7. Add an image sitemap (for large sites)
A sitemap can list the images on each page, which helps Google find images it might otherwise miss, for example those loaded by JavaScript. Add the image namespace and an entry per image:
<url>
<loc>https://example.com/sarees/paithani-green</loc>
<image:image>
<image:loc>https://example.com/img/paithani-saree-peacock-green.jpg</image:loc>
</image:image>
</url>Small sites with normal <img> tags usually don't need this, but it does no harm.
8. Structured data and social tags
For products, recipes, articles and videos, structured data (schema.org) with an image property can make your result eligible for richer displays. Also set an Open Graph image so shared links look good; see our Open Graph guide.
Audit your own pages quickly
Run one of your pages through our extractor to get a list of every image it uses. Look for camera-style file names (IMG_, DSC), heavy PNG photos, missing modern formats, and important images that only appear as CSS backgrounds. Then fix the worst offenders first.
Checklist
- Descriptive alt text on every meaningful image; empty alt on decorative ones.
- Hyphenated, descriptive file names.
- Images placed beside relevant headings, captions and text.
- Modern formats, sensible sizes, width and height set.
- Important images in
<img>, not CSS backgrounds. - Safe lazy loading; hero image loads first.
- Image sitemap and structured data where useful.