ASIC (Application-Specific Integrated Circuit)

An ASIC - Application-Specific Integrated Circuit - is a chip designed to do exactly one thing extremely well. For Bitcoin, that one thing is SHA-256 hashing. A modern Bitcoin mining ASIC chip can do roughly 100 trillion SHA-256 hashes per second, while consuming tens of watts. A general-purpose CPU running flat-out can do maybe a billion hashes per second. The ratio is ~100,000x.

The Bitcoin hardware progression went:

• 2009-2010: CPU mining. Anyone with a laptop could find blocks.
• 2010-2011: GPU mining. Graphics cards turned out to be roughly 50-100x faster than CPUs at hashing. Hobbyists migrated.
• 2011-2013: FPGA mining. Reconfigurable chips offered another 5-10x improvement.
• 2013-now: ASIC mining. The first SHA-256-specific chips launched in early 2013. Anyone still mining with non-ASIC hardware was outcompeted within months.

ASIC mining changed Bitcoin's social structure permanently. Mining went from a hobby to an industry. Operations cluster where electricity is cheapest. Hash rate concentrated in commercial-scale facilities. The "everyone can mine" era ended.

What this buys Bitcoin:

• Massive security budget. Modern ASICs cost thousands of dollars per unit; competitive mining requires industrial deployments. An attacker has to buy and run that hardware against the entire global mining industry to threaten consensus.
• Hard re-purposing. Bitcoin ASICs literally cannot be repurposed for anything else. They're useless except for mining Bitcoin (or other SHA-256 chains). That specialization means the security investment is committed in a way generic hardware isn't.

What it costs:

• Centralization pressure. ASIC supply is dominated by a few manufacturers (Bitmain, MicroBT, Canaan, others). Geographic mining concentration follows electricity prices.
• Energy footprint. Bitcoin's global mining draw is roughly 0.5% of world electricity. Most of it now comes from stranded or low-cost sources, but it's not nothing.

See Mining for the broader picture and Mining Centralization for the structural concerns.