What is Cryptocurrency?
Cryptocurrency is a digital asset that is designed to work as a medium of exchange similar to "normal" currencies like the USD. Unlike "normal" currencies, cryptocurrencies are designed to secure the transactions, to control the creation of additional units of the currency, and to verify the exchange of currency units. This is done using encryption techniques.
Created in 2009, Bitcoin was the first decentralized cryptocurrency. Since then, hundreds of cryptocurrencies have been created. These are commonly referred to as Altcoins.