51% Attack
An attack on a blockchain where a single entity gains control of more than 50% of the network's mining or validation power, allowing them to rewrite transactions, double-spend, or censor blocks. The more decentralized a network, the harder this is to execute.
Mike Starr
Founder, CryptoWizardTools · M.S. Organizational Management
Last reviewed: August 2026
Related Terms
Multi-Sig
Multi-Signature. A wallet security feature requiring multiple private keys to authorize a transaction, reducing the risk of unauthorized access.
ERC-20
A technical standard for creating fungible tokens on the Ethereum blockchain. Most tokens in the DeFi and ICO ecosystems are ERC-20 tokens, including USDT, LINK, and UNI. The standard ensures all tokens work the same way on Ethereum.
On-Chain
Transactions or data that are recorded directly on the blockchain, as opposed to off-chain activities that occur outside the main network.
Seed Phrase
A series of 12 or 24 words generated by a cryptocurrency wallet that serves as a backup to restore access to the wallet. It must be kept secure and private.
Mainnet
The primary production blockchain network where actual transactions occur, as opposed to a testnet used for development and testing.