When we design responsively, our content elegantly and efficiently flows into any device. All of our content, that is, except images. For years, we’ve catered to users with the highest-resolution screens by sending giant images to everyone. No longer. Eric Portis takes us through the new picture element and other attributes to let us mark up multiple, alternate sources. Find out how to use responsive images now: send the best image for each context, cut down on page weight, and speed up performance.
The article that referenced by most when it comes about Responsive Images. It’s probably a complete reference. But WordPress not use all of the features. Especially
Can’t get thorough explanation about
sizes (which the ones used in WordPress), so need another ones.