According to Wikipedia A cryptocurrency is a digital asset designed to work as a medium of exchange that uses cryptography to secure its transactions, to control the creation of additional units, and to verify the transfer of assets.
And according to dictionary 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.
History of Currency
First of all Bartering system was used 6000 BC by the Mesopotamia tribes to exchange goods, services, grains, cattles for another without using any money to fulfill their needs. Barter system also used by the Babylonians. there were some disadvantages of bartering and because of that disadvantages the world thought to solve the problems happens due to bartering. And exactly the
solution was, to make money which could be used among the people. The first form of the money was cowry shells used by China. After the cowry shells the coins was made to use as form of money by the people. Electrum made the first coin. The coin was an alloy of gold and silver. The Lydian state also used the coins as money.