Bitcoin glossary
The total computing power securing Bitcoin, measured in hashes per second.
Hashrate is the combined speed at which all miners are attempting the block puzzle, measured in hashes per second — today in the exahash range (10^18 per second). It is the best single proxy for how much energy and capital stands between an attacker and Bitcoin’s history.
Higher hashrate means rewriting past blocks costs more; the difficulty adjustment keeps block times near ten minutes no matter how much hashrate joins or leaves.