Lightboxes are both loved and hated. They are a valuable pattern to have in the toolbox in some situations. However, they can also be overused and poorly implemented. In Overuse of Overlays: How to Avoid Misusing Lightboxes, Nielsen Norman Group shows a few examples of bad lightboxing as well as some tips for proper use. If you take only one thing away from this article: remember your mobile users before designing a lightbox.