In order for their website to cope up with different devices other than computers, web designers make a separate website for users to view the mobile version of the site whenever a mobile device is detected. Google for example, has its own mobile version for all its domains and services. However, there are a few disadvantages which can cost much of your time because you need to sync whatever it is in your main website to your mobile version each time you add, delete, or modify the site’s design. Are there ways in which you will only use one website and make it respond to any screen size? This is where responsive web designs can be helpful.
Read how responsive web designs can help here: http://www.cheesetoast.co.uk/responsive-web-design-3-column-layout/