Testing of the website at different screen resolutions is very important for every site owner.
There are lots of devices (desktops, notebooks, mobile phones, tablets, TVs, smart watches) with different screen sizes (HD ready, Full HD, 4K) and orientations (portrait, landscape) on the market.
Take a look at free site resolution tester created by our team member: Free Website Tester for Different Resolutions
Check usability of every your website at different screen resolutions, make sure that your websites are adaptive and responsive.