The Domain Name System or DNS is an international address system developed to ensure that every computer connected to the Internet has its own address. DNS assigns addresses to Internet web servers . However, in the DNS system, that address is actually a set of numbers like 126.96.36.199. This set of numbers is called the computer's Internet Protocol (IP) address.
The Domain Name System is most often described as the Internet’s phone book or address book. All of us Internet users use it on daily basis without even realizing it. Its basic task is to convert human-readable website name like coursera.org into its computer-readable numerical IP address like 188.8.131.52.Since such ...view middle of the document...
240.231 (coursera's IP) happens in the background or behind the scene. Try to copy and paste that number in your website browser address bar to see for yourself.
So, your computer uses a DNS server to look up the domain name you are trying access whenever you try to reach a website or send an email. This process is known as DNS name resolution, and we would say that the DNS server resolves (translates) the domain name to the IP address.
Your computer will likely use the DNS server provided by your Internet service provider (ISP). It will use your router as your DNS server if you are behind the router. Your router is probably forwarding your requests to your ISP's DNS servers. The DNS request doesn't happen each time you connect to coursera.org or facebook.com because your computer caches DNS responses. Once it's determined the IP address assigned to a domain name, it will remember it for some time. Thus next time you decide to visit coursera.org it needs to connect only to Coursera, not its DNS server first. This improves connection speed by skipping the DNS request phase. 
The power of this system lies in the simple fact that every single computer or machine (cell phone, Xbox game, fax machine, etc) connected the Internet has its unique IP address in both the IPV4 and IPV6 standards which are managed by Internet Assigned Numbers Authority (IANA) .
Therefore we can compare IP address to a car license plate or telephone number as it:
• shows ownership,
• allows the machine to be located by other machines, and
• enables authorities to track and protect people's safety. 
IP addresses have two formats:
• IPV4 format of IP address has four numbers separated by decimals (dots). Example: 184.108.40.206
• IPV6 addresses are more complex and are comprised of 8 hexadecimal numbers separated by colons. Example: 2002:6B15:F0E7:0:0:0:0:0
If we compare an IP address to a phone...