What Is a Cryptocurrency
Bitcoin is not a coin. It is a system.
An open network of nodes, a public ledger, ownership by key, mining, and a hard limit on how much can ever exist. You already know why it was built. This is how the parts hold each other up.
The problem
Take one part out.
Five components, one rig. Remove any one of them and something specific stops working — a different thing every time. Tap a part to knock it out, tap it again to put it back.
🧩 The Bitcoin system
ALL FIVE IN PLACEParts tried 0 / 5 — they do not fail the same way.
Everything is in place. Knock a part out and read what follows.
Five removals, five different failures. Nodes enforce the rules, the chain carries the history, keys prove entitlement, mining fixes the order, and the supply schedule makes the money predictable. Not one of them can stand in for another — and only the last leaves anything running at all, which is exactly why Bitcoin is a system rather than a coin.
The definition
Three things the system makes true.
Tap each card for what is actually going on underneath.
Hands on
Walk one payment through the parts.
Four stages, in order. Step through them and watch the chain fill in.
No account is opened anywhere along that route. The network checks itself.
The bridge
The whole system in five answers.
Each one names the part that replaces something a bank used to do — and the last one is honest about the cost.
Powerful design, not a perfect system. Because the price swings, bitcoin is hard to use as an everyday unit of account, and scarcity is not the same thing as price stability. Next comes the comparison this section has been circling: this system set beside the digital money already sitting in your bank account. Later lessons open up the blocks and transactions themselves.
Check yourself
Five questions.
Answers come straight from this lesson. Submitting completes it.