Every device that has internet access has an IP (Internet Protocol) address; it is like a phone number assigned to your computer. Websites are nothing more than computers that are optimized for hosting web content to anyone who wants to view it; they too have an IP address just like the rest of the devices connected to the internet.
It is easier to remember a phone number by adding it as a contact. Having to remember that the person you want to call is named Amanda is easier than memorizing (403) 334-8394; this is the principal that the DNS (Domain Name System) works on. It is far easier to remember Facebook.com instead of 184.108.40.206:80
Someone has to have this very large contact book to give other people copies when they request to find a certain website’s IP address, this is why there are 13 root server clusters that hold this information. These root servers have copies of all the websites on the internet and their corresponding IP addresses. If we had to talk to these root servers every time we wanted to access our favorite sites our web browsing experience would be slower; to combat this your computer stores the IP addresses of sites you visit so you only need to talk to these root servers once. However talking to the root servers is actually less common than you might think since most Internet providers have their own DNS servers that you ask instead since they are faster and reduce load on the root servers.
It is important that DNS servers be completely secure from tampering since a record could be altered by a hacker so the IP address to a website such as Facebook could be changed to an identical looking website, when it is really a malicious website created and controlled by the hacker.