Lightboxes are generally built using Javascript, but depending on the author/version/script, lightbox plugins can sometimes cause conflicts with other plugins and themes when used with WordPress.
CSS3 Lightbox is the first lightbox plugin for WordPress that is powered purely by CSS3, making it super fast and lightweight. It doesn’t require any Javascript whatsoever and provides a beautiful experience on mobile.
How does the CSS3 Lightbox plugin work?
The plugin parses all your images in your content and creates some specific classes which are called from a CSS file. It then uses browser native CSS3 functionality to display images in a lightbox, which makes it faster than any Javascript lightbox plugin out there.
You can test out a demo of the CSS3 lightbox by clicking on the image in the post on the demo page.
The CSS3 Lightbox plugin currently works with any embedded image in WordPress content. The plugin’s author is working to make it compatible with gallery images, a feature that will be added in its next release. There’s nothing more annoying than staring at a loading image, waiting for a Javascript-powered lightbox to load. The delay may even cause visitors to leave the page and navigate away from your site. Check out the CSS3 Lightbox plugin for a much faster alternative.
I’m still hooked on http://wordpress.org/plugins/responsive-lightbox/