A cryptocurrency is a medium of exchange like currency that has no physical form. Unlike currency, cryptocurrency is not controlled by any central government or authority.
Bitcoin, the first cryptocurrency to be introduced, was invented by Satoshi Nakamoto in 2008. It is the most valuable and popular digital currency worldwide due to its decentralized nature (there are no banks or government regulators). This novel creation uses cryptography for security. A person needs both the public key and private key to send or receive bitcoin payments.