Crypto is a shortened name of the term cryptocurrency which is a digital currency that uses cryptography that is used over the internet as an alternative to conventional currencies. Conventional currencies are printed and managed by country central banks, while cryptocurrencies are produced, tracked and managed through a "distributed ledger" such as blockchain. While currency transactions of conventional currencies is considered private and closed, cryptocurrencies are considered transparent and open with every blockchain user has the same copy of of the entire blockchain as everybody else but without revealing personal identifying information. This maintenance of the history of transactions involves a process called mining, which can involves blockchain miners who add transaction data to global public ledger of past transactions through an energy intensive computer process. Their is no limit to the number of digital currencies that can be created with most with most consumer and institutional demand behind the largest digital currencies.
In practice , cryptocurrency exchanges can provide digital currency services like Binance, Kraken, Coinjar and other cryptocurrency provides act to enable a consumer or institution to buy the largest in demand cryptocurrencies such as Bitcoin, Ethereum, Tether and XRP. They also provide cryptocurrency to fiat trading as digital currency trading is usually sourced from conventional currencies originally.