What is a blockchain, actually

Forget the buzzwords. A blockchain is a shared notebook that thousands of computers keep identical copies of. When someone sends a coin, the transaction gets written into the notebook, and everyone's copy updates. Nobody can secretly erase a page or edit history, because everyone else's copy would disagree.

That's the whole trick: no bank in the middle, just a public record everyone can check. Bitcoin was the first notebook. Ethereum added the ability to write little programs into it (smart contracts). Solana made a very fast notebook, which is why memecoins live there.

What this means for you: everything you do on-chain is public and permanent. That's a feature — and, if you're careless, a leash. Remember both.