Key features of Bitcoin include:

1. Decentralization: No single entity controls Bitcoin. Transactions and the issuance of new Bitcoins are collectively managed by the network.

2. Limited Supply: There will only ever be 21 million Bitcoins in existence, making it a deflationary currency. This scarcity is programmed into the protocol.

3. Security: Transactions are secured through cryptographic techniques, ensuring the integrity and authenticity of the data.

4. Pseudonymity: Users can hold Bitcoin in wallets identified by alphanumeric addresses rather than personal information, providing some level of privacy.

5. Global Transactions: Bitcoin can be sent or received across borders without the need for intermediaries like banks, and transaction fees are typically lower compared to traditional banking systems.

6. Volatility: Bitcoin's value is known for experiencing significant price fluctuations. This has made it both a speculative investment and a potential hedge against inflation.

People use Bitcoin for various purposes, including online purchases, investments, remittances, and as a store of value. However, its adoption and acceptance as a mainstream form of payment and store of value have been evolving over the years.

Keep in mind that the cryptocurrency space is constantly changing and evolving. For the most up-to-date information, I recommend checking reliable sources or news outlets to see how the Bitcoin ecosystem has developed beyond my last update.