No definition in earlier IP projects. ITrust definition not yet developed.
- Blockchain Technologies 2016 (†789 s.v. "Difficulty" ): Difficulty, in Proof-of-Work mining, is how hard it is to verify blocks in a blockchain network. In the Bitcoin network, the difficulty of mining adjusts verifying blocks every 2016 blocks. This is to keep block verification time at ten minutes.
- Buterin  (†818 s.v. "Blockchain and Mining" ): The main difference between Ethereum and Bitcoin with regard to the blockchain architecture is that, unlike Bitcoin, Ethereum blocks contain a copy of both the transaction list and the most recent state. Aside from that, two other values, the block number and the difficulty, are also stored in the block. (†2349)