When to use CSS background-image?

In what situations is it more appropriate to use an HTML IMG tag to display an image, as opposed to a CSS background-image, and vice-versa?

If the image is part of the content such as a logo or diagram or person (real person, not stock photo people) then use the tag plus alt attribute. For everything else there’s CSS background images.

The other time to use CSS background images is when doing image-replacement of text eg. paragraphs/headers.