A shared ledger nobody owns

A blockchain is a database with one special property: no single person or company controls it. Instead, thousands of computers around the world each keep a full copy and agree on every change together.

Think of a shared notebook in a classroom where every student has an identical copy. When someone writes a new entry, everyone checks it and copies it down. Cheating is nearly impossible because you would need to convince the whole class to change their copies at once.