Congratulations! You learned about how transactions work in the blockchain and some of the mechanisms that keep a blockchain valid and secure.

Let’s review the key terms:

• Transaction: An exchange of value among participants on the blockchain network.
• Participants: Individuals accessing the blockchain network through computers to exchange value.
• *Unconfirmed: *Blocks and transactions that are yet to be verified.
• Consensus: The process of agreeing to the transactions on the blockchain network.
• Hashing: Generating a random string of characters from a given input.
• Immutable: Something whose records can’t be changed.
• Recalculating Hashes: Replacing the incorrect hash with a “correct” one to validate the chain.
• Proof-of-Work: A security feature in blockchain to prevent attackers from easily taking over the blockchain.
• Trustless: A feature of blockchain that states how the system doesn’t rely on any participant to verify transactions.
• Longest Chain: The most trusted chain with the largest amount of computational work done in calculating the Proof-of-Work.