A DApp is an application whose backend logic runs on a blockchain through smart contracts, without a single central server or controlling owner. The code is open and operates according to predefined rules.

Double spending is an attempt to spend the same coins twice. This is a key problem of digital money, which the blockchain solves using a distributed ledger and transaction confirmations.

HODL is a slang term for the strategy of holding cryptocurrency long-term without selling during market swings. The term has become iconic in the crypto community and describes the "buy and hold" approach.

Deflation is a sustained decline in the general level of prices in an economy over time, in which the purchasing power of the monetary unit grows. The phenomenon, the opposite of inflation, is often built into the design of cryptocurrencies.

DDoS is a distributed attack in which many devices simultaneously flood a server with requests to overload it and make it unavailable to ordinary users. It is a frequent threat to crypto exchanges and pools.