Before DNS, the Internet ran on a single text file.
You wanted a hostname?
You emailed Elizabeth Feinler’s team at SRI. They edited their local HOSTS.TXT and then everyone downloaded the new copy!
That worked… until it didn’t.
By 1983, it was obvious this wouldn’t scale, so Paul Mockapetris created DNS: distributed, hierarchical, no single point of failure.
The modern Internet exists because we stopped relying on one file to keep it all straight!