Here are some of bitcoin units
Bitcoin BTC 1
milliBitcoin mBTC 0.001
microBitcoin uBTC 0.000001
Finney 0.0000001
Satoshi 0.00000001
Algorithmic Max 20,999,999.9769 bitcoins
Original Block Reward 50 bitcoins
Current Block Reward 25 bitcoins
Around the year 2140, all available bitcoin will be in circulation and there will be no new coins left to extract from mining rewards.