How to distinguish between virtual currency, digital currency and cryptocurrency

Virtual currency is a non-real currency. It includes digital currency and cryptocurrency. Virtual currency is invisible relative to the physical currency. Also, it is intangible, hence it is so-called virtual currency. For example, online game coins, such as SNDA’s coupons, as well as Tencent’s Q coins, Q points and so on. Even the fictional currency in comics is considered virtual currency. Virtual currency contains digital currency.

Digital currency, which is the currency that emplements digital technology and is generated by computer programs and circulated on the Internet. In general, for example, the gold coins in online games, Q coins by Tencent, Bitcoins, are all digital currencies.
Cryptocurrency, that it is included by virtual currency or digital currency and has the smallest range. It should only be based on blockchain technology (including cryptography, encryption algorithms). Therefore cryptocurrency are the blockchain currencies such as Bitcoins and Ethereum. The key to determine whether a currency is cryptocurrency is to identify if it applied blockchain technology and decentralized. For example, the Q coins issued by Tencent, which is a kind of virtual currency in terms of its imvirtuality. It’s also a digital currency because it was generated by computer programs and can be circulated on Internet to buy products. However, it is not belong to cryptocurrency, because it didn’t implement any blockchain technology.

If a currency adopts blockchain technology, but it is not decentralized, it is only a virtual currency; if blockchain technology is adopted and decentralized, it is cryptocurrency; if it is still centralized, it is only digital currency, such as a country has issued a national digital currency, which is under the control of this nation.