Written retrospectively for the 2004 archive.

Before adding a photo to a page, open it at the size you expect the reader to see. A large original can look fine when the browser scales it down, while the visitor still has to download the whole file.

Make a resized copy, leaving the original alone. Compare the file sizes and open both versions next to the page text. If the small copy is clear enough for the article, use it on the page and link to the original only when a larger view is useful.

Write alternative text that fits the reason the image is there. A screenshot that demonstrates a broken layout needs a description of the problem. A picture that’s simply decorative can use an empty alternative. Try reading the page without the image and see whether it still makes sense.