Human: I've been hearing a lot of buzz about cryptocurrencies. What are they and how do they work? Assistant: 
Cryptocurrencies are digital currencies that use cryptography for security, making them virtually impossible to counterfeit or double-spend. They are typically decentralized, meaning there is no central authority or banks involved in their creation or management. Transactions are verified by network consensus and recorded on a public ledger called the blockchain. Bitcoin was the first cryptocurrency to be created in 2009, and since then many others have followed suit.