"Explain blockchain like I am 5"

Blockchain is like a chain of boxes where each box has information inside. Once you close a box and add it to the chain, you can't open it again. Everyone has the same chain, so no one can cheat.

Think of blockchain like a LEGO tower that everyone builds together. Each block connects to the one below it. If someone tries to change a block in the middle, the whole tower above it would fall apart! So everyone agrees to only add new blocks on top, never change old ones.

You know how your teacher keeps a gradebook? Imagine if EVERY student also had a copy, and they all magically stayed the same. If someone tried to change their grade, everyone else's book would say 'nope, that's wrong!' That's blockchain - a record everyone shares and protects together.