Bitcoin is known as a type of cryptocurrency because it uses cryptography to keep it secure. There are no physical bitcoins, only balances kept in a public ledger that everyone has transparent access to (although each record is encrypted)
I also learned that no one knows who invented Bitcoin, or at least not conclusively. Sotoshi Nakamoto is the name associated with the person or group of people who who released the original Bitcoin white paper in 2008 and worked in the original Bitcoin software that was released in 2009.
