Bitcoin Tutorials - Herong's Tutorial Examples - v1.06, by Herong Yang
Proof of Work Rule - Find a Small Hash Value
This section describes the Proof of Work Rule - Finds a nonce that result a small SHA256 hash value.
The third important Bitcoin Consensus Rule is the Proof of Work Rule: The block hash must meet the cryptographic difficulty requirement. As of 2018, the block hash must be less than or equal to 0x0000000000000000007fffffffffffffffffffffffffffffffffffffffffffff.
Details of the Proof of Work Rule are described below:
As you can see, the main objective of the proof of work rule is to ensure that it will take about 10 minutes to generate, or mine, a new block consistently over time.
As of now, the current Bitcoin difficulty is 3007383866429.732, which can be mapped roughly to a hash target of 0x0000000000000000007fffffffffffffffffffffffffffffffffffffffffffff.
See the "Bitcoin Difficulty Wiki" article at https://en.bitcoin.it/wiki/Difficulty, on how to convert difficulty to hash target.
Table of Contents
What Are Bitcoin Consensus Rules
Controlled Supply Rule - Total of 21M BTC
Mining Reward Rule - Start with 50 BTC
►Proof of Work Rule - Find a Small Hash Value