HIVE uses 2 cryptographic currencies: HIVE and HBD
Typically they are referred to as “TOKENS”.
The “reward system” (detailed below) distributes new tokens each day.
Each user has a wallet where those tokens exist… all wallets are openly viewable to all.
These tokens can be bought and sold on 3rd party websites called exchanges. (binance, bittrex, blocktrades etc)
Because you can exchange for currencies like the US dollar they have a USD value. That value fluctuates (more info below)