The network hashrate is the total computing power that all miners worldwide contribute to the Bitcoin network - mining is done exclusively with specialised SHA-256 ASICs. It is by far the largest computing power of any proof-of-work network and is regarded as Bitcoin's security measure par excellence: the more independent computing power, the more expensive any attack attempt becomes. For miners this also means: a rising hashrate means more competition for the same daily payout - earnings per terahash decline.
Bitcoin adjusts difficulty every 2,016 blocks - roughly every two weeks - so that a block is found every ten minutes on average. If the hashrate rises, difficulty follows suit; if it falls, difficulty falls too. In the chart above you can switch between both metrics and see the relationship across the whole history.
Roughly every four years - exactly every 210,000 blocks - Bitcoin halves the block reward. Past halvings are marked in the chart, and the countdown above shows the calculated date of the next one (spring 2028). For miners, the halving is the most important predictable event: the daily BTC payout halves on a set date. What this means for a specific device can be calculated in the Bitcoin Mining Calculator.
The chart above goes back to the network's early years and shows the path from the CPU era through GPU to today's ASIC era - with a freely selectable time range and an optional price overlay. This also makes visible that hashrate and price often, but not always, move in lockstep; both metrics should always be considered together, never in isolation.