Electronic payment systems and digital currencies are growing in popularity and use. Digital currencies like Bitcoin offer advantages like low transaction fees, anonymity, and lack of centralized control but also risks like volatility and lack of consumer protections. There are over 300 different cryptocurrencies that differ in features like transaction irreversibility, emission limits, and mining processes. The top currencies are Bitcoin, Litecoin, and Peercoin, with Bitcoin dominating the market. Cryptocurrencies provide near zero-cost international transactions without intermediaries but also come with drawbacks like inability to recover funds with unscrupulous users.