When using Retina Display devices, you can see that other sites online appear blurry. This is because of the low-resolution images being stretched to fill the screen that makes the site look disgusting. A Retina Display scales 1px to 2px, making the size double.
These days the popularity of gadgets with retina displays changed the way designs are made. This new advancement requires an increase in every pixel used in a design. Mass production of high-resolution screens, tablets, and smartphones demands web designers catch up.