the DNS (domain name server) system is like the internet's 'phone book'
when you telephone someone you use a number not a name, yes?
if you want to call 'John Doe' and you do not remember the number you look it up in a 'phone book' a cross reference between the name and the number
DNS is the internets 'phone book'
you type in gaggle.com and DNS looks up the number that corresponds with that website