BTC, or Bitcoin, is a digital currency created in 2009 by an anonymous person or group of people under the pseudonym "Satoshi Nakamoto". Bitcoin is the world's first cryptocurrency and has led to the emergence of many other digital currencies.

Bitcoin operates on blockchain technology, a distributed digital ledger that records all transactions in a secure and transparent manner. Bitcoin features include:

1. Decentralization: There is no central authority controlling Bitcoin, making it independent of governments and banks.

2. Confidentiality: Transactions can be made semi-anonymously, as they do not require personal information.

3. Maximum supply: Only 21 million Bitcoins will ever be issued, making them vulnerable to scarcity.

Bitcoin is used as a medium of exchange, as an investment, and also as a tool for cross-border money transfers. However, its value fluctuates greatly, making it a subject of controversy and debate in the fields of economics and technology.