The private key is the password required to buy, sell, and trade the bitcoin in a wallet. When you go to make a purchase using bitcoin, that network of computers rushes to check that your transaction happened in the way you said it did. What is the blockchain? If you want to try Coinbase but with much higher volume, this platform is the way to go. In February , the company expanded into the bitcoin and ethereum markets, along with market data for another 15 currencies, allowing users to trade cryptocurrency without a fee. The Cash App allows users to buy and sell bitcoin without processing fees.