What is a blockchain?
A blockchain is a shared record organized into linked groups called blocks. Network participants check transactions against agreed rules. In Bitcoin, confirmed transfers become part of this record, allowing wallets to determine which funds can be spent. The links between blocks help make rewriting earlier history difficult.
Remember this
The blockchain is the record; it is not the same thing as a wallet.
Further reading: Bitcoin.org — How Bitcoin works · Reviewed October 10, 2026
Written lesson available. Matching TCS video coming later.