If you code websites, it’s a good bet that at least one of your clients has asked about or requested a mobile-friendly website. If you go the responsive design route (whereby your website is flexible enough to adjust visually from mobile to desktop widths), then you’ll need a strategy to make images flexible, too — a responsive image solution.

http://mobile.smashingmagazine.com/2013/07/08/choosing-a-responsive-image-solution/