What is an ASIC miner?
A machine built to do nothing but Bitcoin mining: chips that hash trillions of times a second, far beyond any ordinary computer.
Early miners used CPUs, then graphics cards. Since 2013 the race has belonged to ASICs — application-specific integrated circuits — whose only job is SHA-256 hashing. A general-purpose computer can no longer compete.
ASICs are why mining is an industry: they cost money, need cheap electricity and go obsolete within a few years. Owning one isn't required — the network's work shows up as hashrateHashrateHow many guesses a second all of Bitcoin's miners make together. More hashrate makes the network harder to attack. whether or not you run machines.