Cryptocurrency is a digital currency that uses cryptography for security. It allows for decentralized control without a central authority like a bank. The first cryptocurrency, Bitcoin, was created in 2009 by Satoshi Nakamoto as a way to conduct financial transactions without intermediaries. Cryptocurrencies use blockchain technology which achieves consensus in a decentralized network to prevent double spending. They have the potential to revolutionize the global economic system by taking control away from central authorities and giving individuals freedom and power over their money.