DNS · Domain Name System
/ dee-en-ESS /
DNS is the internet's phone book. You type a friendly name like example.com, but computers don't actually find each other by name — they find each other by number, an IP address like 93.184.216.34. DNS is the system that quietly looks up the name and hands back the number, every single time, before your browser can connect to anything.
It works because nobody wants to memorize a dozen numbers just to visit their favorite sites. Names are for humans; numbers are for machines. So whenever you click a link or load an API, the very first invisible step is a DNS lookup: 'what's the IP for this name?' Only once that answer comes back can the real request go out. It's so fast and automatic that you forget it's happening — until it doesn't.
And that's the practical bit to remember: a surprising number of 'the site is down' moments are really DNS problems — a name that points at the wrong number, or a fresh domain whose entry hasn't spread across the world's servers yet (people call that 'waiting for DNS to propagate'). When something connects to the wrong place, or to nothing at all, the phone book is the first place to look.
$ dig +short example.com 93.184.216.34 # the name you typed → the number your browser actually connects to
Look up a name and watch the phone book hand back its number.
'Waiting for DNS to propagate' just means the world's nameservers haven't all heard your new entry yet — give it a few hours.