Every 2,016 blocks, the Bitcoin protocol alters the algorithm’s difficulty, adjusting it up or down depending on how long it took, on average, for the network to find the previous 2016 blocks. If the hashrate has fallen, difficulty declines, which speeds up block creation. That brings it back to the average 10 minutes per block that the system is designed to sustain over time and ends the squeeze on fees. The opposite occurs when the hashrate has risen.
