Cryptocurrency is a medium of exchange, created and stored electronically in the blockchain, using encryption techniques to control the creation of monetary units and to verify the transfer of funds.
To prevent fraud and manipulation, every user of a cryptocurrency can simultaneously record and verify their own transactions and the transactions of everyone else.
Because the data is public and maintained by many thousands of people, transactions are permanent and very secure.
With public records, cryptocurrencies don’t require you trust a bank to hold your money. They don’t require you trust the person you are doing business with to actually pay you. Instead, you can actually see the money being sent, received, verified, and recorded by thousands of people. This system requires no trust.