Bitcoincore.

Programmed into the Bitcoin core protocol every 210,000 blocks (roughly every four years), the halving cuts miner block subsidies in half—from 50 BTC originally down through 25, 12.5, 6.25, and currently 3.125 BTC per block. This programmatic supply shock permanently restricts incoming new issuance until the 21 million limit is reached.

Altering the 21 million hard cap would require consensus among tens of thousands of independent economic node operators running the Bitcoin software worldwide. Any hard fork attempting to inflate supply would be rejected by non-mining verifying nodes, rendering modified tokens incompatible with the canonical Bitcoin ledger.

Spot ETFs permit regulated financial institutions, wealth advisors, and retirement pension funds to gain direct spot economic exposure through standard brokerage accounts. ETF authorized participants must purchase and store physical Bitcoin in audited custodian vaults, transforming OTC flows into transparent public balance sheets.

Every 2,016 blocks (approximately two weeks), the Bitcoin network recalculates the computational difficulty required to find a valid block hash. If total global hash rate rises and blocks are solved faster than the 10-minute target, difficulty automatically increases; if miners disconnect, difficulty drops, guaranteeing clockwork monetary issuance.