Just like how one whole $ Dollar is divisible into ¢100 Cent
One whole ฿ Bitcoin is divisible
into 100,000,000 Satoshis
One Dollar is the same as 100 Cent
100 Cent is the same as one Dollar
100,000,000 Satoshis is the same as one Bitcoin
One Satoshi is the same as 0.00000001 of a Bitcoin
If you buy 0.025 Bitcoin it's the same as buying 250,000 Satoshis