user60574: I encountered 'millisatoshi' (msat) while browsing Lightning Network..., see screenshoot below:

And subsequently I found it mentioned here: 
https://github.com/ElementsProject/lightning/blob/master/README.md#sending-and-receiving-payments
Obviously, I am curious... I thought satoshi is the smallest unit?

user51948: It's not a mistake, it's literally a thousandth of a satoshi. A satoshi is the smallest unit for bitcoin, but lightning can transact with even smaller units while channels are open. The amount is rounded down to the nearest satoshi when the channel is closed and broadcast to the blockchain to adhere to bitcoin's limit.

60574: <p>I encountered 'millisatoshi' (msat) while browsing Lightning Network..., see screenshoot below:</p>

<p><a href="https://i.stack.imgur.com/prrXi.png" rel="noreferrer"><img src="https://i.stack.imgur.com/prrXi.png" alt="Taken from https://lnmainnet.gaben.win/"></a></p>

<p>And subsequently I found it mentioned here: </p>

<p><a href="https://github.com/ElementsProject/lightning/blob/master/README.md#sending-and-receiving-payments" rel="noreferrer">https://github.com/ElementsProject/lightning/blob/master/README.md#sending-and-receiving-payments</a></p>

<p>Obviously, I am curious... I thought satoshi is the smallest unit?</p>
 51948: <p>It's not a mistake, it's literally a thousandth of a satoshi. A satoshi is the smallest unit for bitcoin, but lightning can transact with even smaller units while channels are open. The amount is <a href="https://github.com/lightningnetwork/lnd/blob/master/lnwire/msat.go#L22-L24" rel="nofollow noreferrer">rounded down</a> to the nearest satoshi when the channel is closed and broadcast to the blockchain to adhere to bitcoin's limit.</p>
