Below is an example of how to embed both a retina and non retina image with only one of the images displaying on screen depending on your screen's resolution.
<img src="https://www.karenkirkness.com/wp-content/uploads/2017/10/facebook2.png" srcset="https://www.karenkirkness.com/wp-content/uploads/2017/10/facebook1.png 2x" />
facebook2.png is the non-retina image and facebook1.png is the retina image.
This is a good way to add social media links in footer widgets etc.