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."
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.
Bitcoin is the world’s first virtual digital currency underpinned by a completely decentralized blockchain technology also known as the Distributed Ledger Technology (DLT). Bitcoin was first created in 2009 by an anonymous identity of Satoshi Nakamoto. Bitcoin allows for peer-to-peer transactions and is completely free of any third-party involvement like financial institutions or central banks. The Bitcoin’s blockchain network maintains a history of all the transactions made and facilitates instant funds transfer with minimal transaction fees required to cover the cost of network operation. The total supply of Bitcoin is fixed at 21 million coins and its smallest fractional unit is called as Satoshi. Each Satoshi is a hundred millionth of a Bitcoin which means 100,000,000 Santoshi = 1 BTC. Bitcoins are generated by a process known as ‘mining’ which involves solving of complex mathematical algorithms. The miners involved in the mining process look after the Bitcoin network security and validate each transactions taking place on the network. Bitcoin can be exchanged with other digital currencies or fiat currencies. Bitcoin is used as a means of payment by over 100,000 vendors and merchants.
Because the blockchain works by verifying transaction history, and this verification process is labor-intensive and slow, only so many transactions can be verified in a certain timespan. So, if you sell your Bitcoin, but the purchase isn’t confirmed by the blockchain network, and the price of the currency changes, the sale won’t process. You'd have to sell your Bitcoin at whatever the new rate is (if you so choose to sell). Also due to the reality of blockchain, as well as for other reasons thus far unidentified, the Coinbase payout system can sometimes be unreliable. There have been reports of extensively delayed payout periods, and bugs sometimes keep the site from running as efficiently as it could or should. A word to the wise: if you are going to invest in and speculate on cryptocurrencies, do so carefully.
Bitcoin mining saps energy, costly, uses more power and also the reward delays. For mining, run software, get your wallet ready and be the first to solve a cryptographic problem and you get your reward after the new blocks have been added to the blockchain.Mining is said to be successful when all the transactions are recorded in the blockchain and the new blocks are added to the blockchain.