Cryptocurrency is a digital or virtual currency that uses cryptography for security. Cryptography is the practice of secure communication in the presence of third parties. Cryptocurrencies use decentralized technology called blockchain, which allows for secure and transparent transactions without the need for a central authority such as a bank.

Cryptocurrencies have gained popularity in recent years, with Bitcoin being the most well-known. However, there are now thousands of different cryptocurrencies available, each with its own unique features and use cases.