Hash
A unique, fixed-length string produced from any input data using a mathematical function. The smallest change to the input completely changes the hash, which is why it is used to verify the integrity of blocks and transactions.
See also
Bitcoin
The first and most well-known cryptocurrency, created in 2009 by an anonymous author (or group) under the pseudonym Satoshi Nakamoto. It works without a central bank or intermediaries — every transaction is recorded on a public blockchain.
Blockchain
A distributed database made up of a chain of blocks containing transaction data. Each new block references the previous one, which makes altering past records nearly impossible without the agreement of the entire network.
Transaction
A record of a cryptocurrency transfer from one address to another. Once confirmed by the network, a transaction becomes part of the blockchain and can no longer be reversed or altered.
Wallet
Software or a device for storing the private keys that give access to cryptocurrency on the blockchain. The coins themselves are not physically "stored" in the wallet — it only holds the keys needed to control them.
Private key
A secret code that proves ownership of cryptocurrency and allows you to sign transactions. Whoever knows the private key has full control over the funds — it should never be shared with anyone.