"A digital currency in which encryption techniques are used to regulate the generation of units of currency and verify the transfer of funds, operating independently of a central bank."
A cryptocurrency is a form of digital asset generally intended to be used as a medium of exchange in much the same way traditional currencies are. Often they are also held as assets by investors who expect the cryptocurrency to increase in value over time. Cryptocurrencies rely upon the cryptography used within a blockchain; the way in which cryptography is used alongside certain other protocols ensures that these assets have characteristics desirable in a digital currency (e.g security, transferability and immutabillity).
Cryptocurrencies first came to prominence when the first decentralized cryptocurrency, Bitcoin, was created in 2009 by the anonymous person or persons, Satoshi Nakamoto. Since then, multiple alternative cryptocurrencies (or 'altcoins') have been created and cryptocurrencies have seen increasingly widespread adoption, coinciding with massive financial gains in value as a whole. In early 2011 a single Bitcoin was worth $1 USD. As at September 2018, Bitcoin trades at a value of $6,300 USD per coin.