In the case of Bitcoin, miners run computer programs to verify the data that creates a complete transaction history of all Bitcoin. A technology known as the blockchain, which is used to create irreversible and traceable transactions, makes the process of verification possible. Once a miner has verified the data (which comes in a block, hence, blockchain), they are rewarded with some amount of digital currency, the same currency for which they were verifying the transaction history. So mining Bitcoin, for example, would earn you Bitcoin.
Volatility is perhaps the most commonly-cited disadvantage of Bitcoin in terms of its use case as cash. Ironically, that very volatility helped grow the network, providing traders with very lucrative opportunities in short time periods. However, for those wishing to store value and transact Bitcoin as an everyday currency, the volatility is a major drawback.
On February 16, 2018, Coinbase admitted that some customers were overcharged in error for credit and debit purchases of cryptocurrencies. The problem was initiated when banks and card issuers changed the merchant category code (MCC) for cryptocurrency purchases earlier this month. This meant that cryptocurrency payments would now be processed as "cash advances", meaning that banks and credit card issuers could begin charging customers cash-advance fees for cryptocurrency purchases. Any customers who purchased cryptocurrency on their exchange between January 22 and February 11, 2018 could have been affected. At first, Visa blamed Coinbase, telling the Financial Times on February 16 that it had "not made any systems changes that would result in the duplicate transactions cardholders are reporting." However, the latest statement from Visa and Worldpay on the Coinbase blog clarifies: "This issue was not caused by Coinbase."
Since the Bitcoin creation in 2009, the price of this virtual currency remained quite stable until January 2013, reaching a maximum value of approximately 20 U.S. dollars. Afterwards a monthly price growth was observed until October 2013 when the price reached 198 U.S. dollars. This nearly tenfold increase in Bitcoin value proved to be insignificant in comparison to the price rally in November 2013, when the threshold of 1,100 U.S. dollars per coin was broken. After a period of downtrend which followed, Bitcoin price reached 1,349.19 U.S. dollars in April 2017.