blockchain A blockchain is a type of distributed ledger technology (DLT) that consists of growing lists of records, called ''blocks'', that are securely linked together using cryptography. Each block contains a cryptographic hash of the previous block, a ...

technology, a testnet is an instance of a blockchain powered by the same or a newer version of the underlying software, to be used for testing and experimentation without risk to real funds or the main chain. Testnet

coins A coin is a small, flat (usually depending on the country or value), round piece of metal or plastic used primarily as a medium of exchange or legal tender. They are standardized in weight, and produced in large quantities at a mint in order to ...

are separate and distinct from the official (''mainnet'') coins, don't have value, and can be obtained freely from ''faucets''. Testnets allow for the development of blockchain applications without the risk of losing funds. A bug was discovered in the

Bitcoin Core Bitcoin (abbreviation: BTC; sign: ₿) is a decentralized digital currency that can be transferred on the peer-to-peer bitcoin network. Bitcoin transactions are verified by network nodes through cryptography and recorded in a public distrib ...

software that gave miners the ability to take down essential parts of the Bitcoin infrastructure (nodes) by sending a 'bad' block to the blockchain.

References

{{cryptocurrency-stub Blockchains