Cryptocurrencies are digital currencies that use cryptography to ensure secure transactions. The first and most well-known is Bitcoin, created in 2009. Since then, many others have emerged such as Ethereum, Binance Coin, Solana, and Cardano, each with distinct functions and technologies. Some focus on smart contracts, others on fast transactions or privacy. They are based on blockchain technology, a decentralized system that records all operations. They are not controlled by governments or banks, making them attractive to some users, but also volatile. Cryptocurrencies can be used for investing, transferring money, or acquiring goods, although their legality and acceptance varies by country. Despite their growth, they continue to generate debates about security, sustainability, and regulation.$BTC $ETH $BNB