Bitcoin’s hash rate is a measure of the speed of the combined computer processing of miners keeping the network in operation.
Hash rate is measured in hashes per second. Hash rates falling could indicate miners turning off their machines. Therefore it is an important tool to watch for the fundamental health of the network.
The higher the hash rate, the healthier the Bitcoin network. Steady growth is vital to the network thriving.
Efficiency in mining is even more important than hash rate, as all the power in the world won’t be profitable if it’s more expensive than the cost per BTC.