The story begins a time ago. People use the barter system for trading it was adopted to exchange their services and goods. This system was used for centuries, before the invention of banks before the invention of money.
The barter system does not include money you can buy an item in exchange for other items that you have in excess and you don't want it.

Barter System

Later on Money Invented. Money is one the most fundamental of all man’s inventions. Money acts as a medium of exchange, a parameter, a measure of value, a store of value, and a standard of deferred payments. The barter system was replaced by a money economy. With the invention of money, the direct exchange of goods for goods was given up. A new system of exchange was introduced. Under the new system, a person who has an article to exchange sells it for money, and with the money, he can purchase the commodities he wants.

Money and Note act as a receipt of resources that you have.
Then the money was standardized with gold. Money was like the receipt of gold that you have.

The shift to paper money in Europe increased the amount of international trade that could occur. Banks and the ruling classes started buying currencies from other nations and created the first currency market. The stability of a particular monarchy or government affected the value of the country’s currency, and thus, the ability of that country to trade on an increasingly international market.

Nowadays with the emergence of computer-driven societies that physical receipts are in form of electronic receipts. The 21st century has given rise to two forms of currency. The Mobile Payments and Virtual Currency
So I believe that cryptocurrency is like an electronics receipt of my resources and called virtual currency.

So the “Cryptocurrency” in simple terms is money digital money or virtual currency.
Nowadays famous cryptocurrencies are bitcoin and ethereum.
Cryptocurrency is gaining popularity and in near future, it will replace the old form of currencies.

There is light in every Hollow.