Cryptocurrency is a form of digital currency secured by cryptography, designed to function as a peer-to-peer medium of exchange without banks or governments. The first cryptocurrency, Bitcoin, was launched in 2009 by the pseudonymous developer Satoshi Nakamoto as a decentralized payment system.

Most cryptocurrencies run on blockchain technology, a public and immutable ledger that records all transactions. These networks are maintained by nodes (computers connected to the system), with full nodes performing all verification tasks.

Because cryptocurrencies are decentralized, no single authority controls issuance or management. Instead, they rely on mathematical algorithms and protocols to ensure security, transparency, and resistance to fraud. Levels of decentralization can vary across different cryptocurrencies, depending on their network structure.

In essence, cryptocurrencies combine cryptography, decentralization, and blockchain to enable secure, borderless, and censorship-resistant digital transactions.