But due to the volatility of bitcoin, it’s impossible to predict the annual revenue of a mining farm. On my flight from China back to the United States, the price of bitcoin crashed 25 percent, from $2,400 to $1,800. In no time at all the operation I visited was bringing in $50,000 less per day. Within a week it was back up, and approaching an all-time high.
In addition to being the means of generating new bitcoin, bitcoin mining creates the blockchain that verifies bitcoin transactions. The block reward is gleaned by placing a new block on the blockchain, which acts as an advancing public ledger of verified transaction. This is an essential function for bitcoin's operation as it enables the currency to be safely and predictably created without the centralized regulation in the form of a bank or federal government. Blocks must to be a validated by a proof-of-work (Bitcoin uses Hashcash), which can only be obtained by expending a great deal of processing power. Once a block is obtained a message is broadcast to the mining network and verified by all recipients. 
Mining is a record-keeping service done through the use of computer processing power.[e] Miners keep the blockchain consistent, complete, and unalterable by repeatedly grouping newly broadcast transactions into a block, which is then broadcast to the network and verified by recipient nodes.[64] Each block contains a SHA-256 cryptographic hash of the previous block,[64] thus linking it to the previous block and giving the blockchain its name.[3]:ch. 7[64]
Bitcoin's most important characteristic is that it is decentralized. No single institution controls the bitcoin network. It is maintained by a group of volunteer coders, and run by an open network of dedicated computers spread around the world. This attracts individuals and groups that are uncomfortable with the control that banks or government institutions have over their money.
Hardware wallets are by far the most secure kind of Bitcoin wallet, as they store Bitcoins on a physical piece of equipment, generally plugged into a computer via a USB port. They are all but immune to virus attacks and very few instances of Bitcoin theft have been reported. These devices are the only Bitcoin wallets which aren't free, and they often cost $100 to $200. 
Controlling and monitoring your mining rig requires dedicated software. Depending on what mining rig you have, you’ll need to find the right software. Many mining pools have their own software, but some don’t. In case you’re not sure which mining software you need, you can find a list of Bitcoin mining software here. Also, if you want to compare different mining software, you can do it here.
Electrum gets high marks for its ease of use and user interface, which is always nice, but the real reason it's the best bitcoin wallet for desktop is its safety and reliability. Like any desktop wallet that's worth its salt, users get to control their private key; Electrum doesn't know what it is. Since your private key, a long string of letters and numbers, gives you access to your bitcoin, you need to keep that, you know, private.
But bitcoin is completely digital, and it has no third parties. The idea of an overseeing body runs completely counter to its ethos. So if you tell me you have 25 bitcoins, how do I know you’re telling the truth? The solution is that public ledger with records of all transactions, known as the block chain. (We’ll get to why it’s called that shortly.) If all of your bitcoins can be traced back to when they were created, you can’t get away with lying about how many you have.
Network nodes can validate transactions, add them to their copy of the ledger, and then broadcast these ledger additions to other nodes. To achieve independent verification of the chain of ownership each network node stores its own copy of the blockchain.[65] About every 10 minutes, a new group of accepted transactions, called a block, is created, added to the blockchain, and quickly published to all nodes, without requiring central oversight. This allows bitcoin software to determine when a particular bitcoin was spent, which is needed to prevent double-spending. A conventional ledger records the transfers of actual bills or promissory notes that exist apart from it, but the blockchain is the only place that bitcoins can be said to exist in the form of unspent outputs of transactions.[3]:ch. 5