Cryptocurrency is a virtual currency that allows for digital financial transactions. In other words, it's a form of payment. It is decentralized from banks and credit card companies, and acts as its own medium for security and tracking.
Cryptocurrencies were designed to be a quick, low-cost, and safe way to do peer-to-peer financial transactions while eliminating the need for a third party. All transactions are tracked and stored on a secure ledger (referred to as blockchain) that is public to all users, assuring them that each transaction is verified. Today, three of the most popular blockchain networks include HyperLedger, Ethereum, and R3/Corda.
The first cryptocurrency to be created was Bitcoin, which remains the most popular and valuable to this day.