The private key is the password required to buy, sell, and trade the bitcoin in a wallet. Investing in cryptocurrencies and Initial Coin Offerings «ICOs» is highly risky and speculative, and this article is not a recommendation by Investopedia or the writer to invest in cryptocurrencies or ICOs. Since the rate at which bitcoin can be produced cuts in half every four years, the currency becomes more difficult to obtain over time. Miners need powerful computers and other related gadgets to facilitate mining. BitQuick Popular. When consumers make purchases using the U.