What is DNS? Servers for Domain Names? Where are they?

What is DNS - Domain Name Server?

Webpages are linked and found by a series of numbers, ie 66.43.52.91 is www.website-biz-optimization.com, my IP Address.
You can type either the numbers or the website name into the URL (Uniform Resource Locator) box to find my home page. My pages are listed on a DNS (Domain Name Server) somewhere.
DNS is a database hosted on computers set up for the task in large databases whic find the name www.website-biz-optimization.com and convert it to 66.43.52.91, which the internet routers can read and look for the relevant page