A dynamic website is a website where text and images and formatting can be added / modified by a non technical person. Dynamic websites are very popular with organisations that want to have full control of their website without having to hire or contact Web Designers to make changes on their behalf.

Content Management System (CMS) help organizations by managing content, optimizing business processes and enabling compliance.

What is a static website and why are they cheaper than dynamic site? 

A web page is a document created with HTML (HyperText Markup Language) that is part of a group of documents or resources available on the World Wide Web. Collectively, these documents and resources form what is known as a web site.

While DNS is one of the least necessary technologies that make up the Internet as we know it, it is also true that the Internet would never have become as popular as it is today if DNS did not exist. Though this may sound like a bit of a contradiction, it is true, none the less.