Cryptocurrencies (short: crypto) are digital - virtual currencies based on cryptography and blockchain technology. They are issued in digital form, therefore they can be used for trading, investing in companies and their products, as a method of payment or a form of savings. The term "crypto" comes from the word "cryptography” or “encryption” (cryptography or encryption usually refers to a mathematical approach for information protection). The main feature of cryptocurrencies is that they are decentralized. They don’t depend on centralized authorities such as states or banks. The security and transparency of cryptocurrencies are guaranteed by a decentralized computer network around the world. With the help of blockchain technology, a decentralized computer network prevents the possibility of counterfeiting and manipulation.