Why do people talk in satoshi
B'coz it's a/the unit of bitcoin.
how much is a satoshi worth?
1 satoshi = 0.00000001BTC
= 0.00001mBTC
= 0.01 uBTC
What are satoshi is it a unit?
Basically,
satoshi was/is the founder of bitcoin & henceforth their name is also the "unit" of bitcoin.
P.S. It's like Newton discovered about "Force" & henceforth the S.I. unit of force is "Newton (N)"