This is all part of a UX website. Creating great user experiences

Responsive design is an approach to web page creation that makes use of flexible layouts, flexible images and cascading style sheet media queries. The goal of responsive design is to build web pages that detect the visitor’s screen size and orientation and change the layout accordingly.

Having a site that is mobile responsive will make sure that people on phones, tablets and desktops all get the same experience and you only have to maintain 1 website!