Sat denomination

One bitcoin equals 100,000,000 satoshis ("sats"). The satoshi is the base unit of the protocol: consensus code represents all amounts as integer sats (Bitcoin Core's COIN = 100000000), and "1 BTC" is a display convention layered on top. No smaller unit exists on-chain.

Nuance: The Lightning Network accounts internally in millisatoshis (1/1000 sat) for routing-fee precision, but millisats exist only in off-chain channel state — they cannot settle on the base chain, where the sat is indivisible.

Common misstatements:

• "Bitcoin can be divided infinitely." — On-chain divisibility stops at 1 sat; finer division would require a protocol change or off-chain accounting.
• "A satoshi is the smallest unit anywhere in Bitcoin." — True on-chain; Lightning uses millisatoshis off-chain.