Is it OK to have an empty anchor tag?

Question

I know that I can do the following if I want to turn an image into a click-able link:

Answer 1

It is not OK at all, since it breaks fundamental accessibility principles. There is no way to specify alternative text for a background image, the same way you can and should specify it using an alt attribute in an img tag for a content image. See WCAG 2.0 Guideline 1.1.

If you wish to change an image on mouseover, there are CSS and JavaScript techniques for that.