Another concept that has been introduced with the advent of bitcoin and altcoins is difficulty in retargeting algorithms. In bitcoin, a difficulty target is calculated simply by the following equation; however other coins have either developed their algorithms or implemented modified versions of the bitcoin difficulty algorithm:
T = Time previous * time actual / 2016 * 10 min
The idea behind difficulty regulation in bitcoin is that a generation of 2016 blocks should take roughly around two weeks (inter-block time should be around 10 minutes). If it takes longer than two weeks to mine 2016 blocks, then the difficulty is decreased, and if it takes less than two weeks to mine 2016 blocks, then ...
