What is blockchain technology?
A distributed ledger of time‑stamped transaction blocks maintained across synchronized nodes.
What are nodes?
Connected computers that store the full blockchain and validate transactions.
What is a distributed ledger?
A shared database existing across multiple nodes, not in one central location.
What is a hash function?
A cryptographic function producing a unique fixed‑length output; any input change alters the hash.
How are hash functions used in blockchain?
They generate unique values linking blocks together securely.
What is Proof of Work?
A consensus method requiring nodes to solve complex math problems to validate blocks.
What is Proof of Stake?
A consensus method selecting validators based on how much stake they hold.
What is Proof of Elapsed Time?
A consensus method where nodes wait for a random amount of time to validate a block.
What enables transaction initiation and broadcast?
Asymmetric encryption and digital signatures.
What is a digital signature?
An encrypted form of electronic ID used to authenticate senders.
Is blockchain secure?
Generally yes, unless someone gains majority control of nodes.
What is a 51% attack?
An attack where someone controlling most nodes can change or remove transactions.
Name a blockchain application.
Cryptocurrency, smart contracts, digital identity, NFTs, medical records, supply chain authenticity.
What types of blockchain networks exist?
Public, private, consortium, and hybrid blockchains.
What business value does blockchain create?
Reduces uncertainty via immutable, shared, trusted transaction records.
