Hash rate is a measuring unit that refers to how much power a cryptocurrency network continuously consumes to remain functional. Different cryptocurrencies have different hash rates, that is, they require different overall computation power to function.
To use Bitcoin as an example, the SHA-256 hash of block’s header currently must be a 256-bit alphanumeric string and has to start with eighteen zeros. This target is changed every 2016 blocks.
Crypto miners find new blocks by performing a series of complex computations in order to solve mathematical challenges. To solve (or hash) a block, each machine must perform thousands of small calculations. The successful miner hashes the block’s header in such a way that is equal to or less than the target. The overall power consumption of all the mining machines across the network, which rises and falls in tandem with the number of calculations per second the network performs, is referred to as the hashrate.
One of the contentious issues around cryptocurrency mining, specifically Bitcoin, is the energy use associated with mining equipment and activity. The associated energy costs can also be crippling to miners since the electricity needed to mine a block can be more expensive than the reward the successful miner receives. At points when the Bitcoin price is down (and with it the block rewards), there is less incentive for miners to devote computing power to mining. A good place to learn more about the mining industry and its controversies is Bitrates’ series of articles and interviews about mining in North America.