Every computer which is connected to the Internet has it's own unique IP address. Every website is hosted on a server which also has it's IP. Since it would be hard to remember IP address of ie. google or facebook, DNS was introduced. DNS stands for Domain Name Server and it's purpose is to convert human readable hostname to IP address of server. Local DNS would host own definition of Hostname & IP which computer or computers in some network would use. In Windows, local DNS can be edited in WindowsSystem32driversetchosts