DNS is like a phone book for the internet. When you type "google.com" into your browser, your computer doesn't know where Google is. It knows the name, but not the address. So it asks a special helper: "Hey, where does google.com live?" The helper looks it up and says: "Google lives at 142.250.80.46." That's a number address — like a street address for a building. Now your computer knows where to go. That helper is a DNS server. DNS stands for Domain Name System, but you can think of it as the thing that turns names you can remember into addresses computers can use. Every time you go to a website, this happens first. It's so fast you never notice it. But if the phone book breaks — if DNS goes down — then nothing works, because your computer knows the names but forgot all the addresses.