A CMS is a software platform that lets its users create, edit and publish web pages. Its interface makes interacting with a website's database user friendly.
CMSs use Hypertext Markup Language (HTML) to create what you see and Cascading Style Sheets (CSSs) to create the way in which it is seen. They are the two essential core components which create web pages.
A CMS allows users, without any knowledge of coding, to create and control website content.
We mostly use one or the other of the world's two leading CMSs, Joomla and WordPress.
Simple. We've been building websites since 1998 (flat file sites), and, using CMSs since 2001 (Mambo, the precursor to Joomla), Joomla (2006) and WordPress (2007) and have all of the experience which comes with that. Oh, and a bunch of satisfied clients.
Below find samples of some of my recent websites. All websites have responsive (mobile friendly) layouts.