Cryptocurrency is a digital or virtual form of currency that uses cryptography for security. It operates on decentralized networks based on blockchain technology, which enables secure and transparent transactions without the need for intermediaries like banks. Bitcoin, launched in 2009, is the first and most well-known cryptocurrency, followed by thousands of alternatives, including Ethereum and Litecoin. Cryptocurrencies provide a means of transferring value across borders with low transaction fees and increased privacy, but they also come with risks like volatility and regulatory concerns.