Foundations quiz

A blockchain is a shared transaction history. Your coins are not objects sitting anywhere, they are entries in that history, and your key is what proves an entry is yours.

Every block carries a fingerprint of the previous one. Rewriting an old block invalidates every block after it, which is why depth equals security and why there is no undo.

Receiving needs nothing but your public address. A private key or seed phrase is only ever needed to spend, so anybody asking for one in order to send you something is stealing.

An explorer lets you verify claims rather than trust them. It is the single most useful habit in crypto, because almost every claim about what happened onchain can be checked in seconds.

A block holds a finite amount of activity. Fees are the auction for that space, which is why they rise with demand rather than with the size of the amount you are sending.

Decentralization is about who can stop you, not about speed, cost or safety. It buys you censorship resistance and it costs you the ability to appeal to anyone when something goes wrong.

There is no password reset. That is the direct cost of the thing that makes self custody valuable, which is why the backup matters more than any other single step.

A wrong network selection is by far the most common cause and costs nothing to check. Re-entering a seed phrase into anything because of a zero balance is exactly how the real losses happen.