Cryptocurrencies, which can also be called digital currencies or cryptoassets in some contexts, are a digital means of exchange. They serve the function of a currency, which is why they are known by that name. However, it is something completely digital, which uses cryptographic methods to secure its financial transactions, control the creation of new units, and verify the transfer of assets.
Therefore, we can consider them as a decentralized alternative to digital currencies. By the term "decentralized," we mean that these currencies are not controlled by a single service or company. The same goes for conventional currencies, centralized and organized by entities and banks, which makes them an opposed method to both.
The first cryptocurrency was Bitcoin created by "Satoshi Nakamoto," a pseudonym that corresponds to a person whose exact identity is unknown. This person published an article in 2009 describing a P2P payment system called Bitcoin. After a few months, he himself published the first version of the software that allows managing the currency's network, and he began to interact in forums with the first interested parties.
