Cryptocurrency is a form of virtual currency, where no one person or entity has control over ownership. Cryptocurrencies are built on blockchain technology, which is a distributed ledger of all transactions. The ownership of cryptocurrency is recorded against wallet addresses, similar to traditional bank account information.
The proofs of how much currency is in each wallet, as well as transactions between those wallets all use mathematically-provable cryptographic principles that ensure the integrity and verifiability of this information.
Cryptocurrency can be acquired through mining or currency exchange, and can be spent, held as an investment or sold for fiat currency (traditional currency such as GBP, USD or EUR).