LET ME THROW MORE LIGHT ON BITCOIN MINING...
Bitcoin mining is the process of adding transaction records to Bitcoin's public ledger of past transactions or blockchain. This ledger of past transactions is called the block chain as it is a chain of blocks. The block chain serves to confirm transactions to the rest of the network as having taken place.
Bitcoin nodes use the block chain to distinguish legitimate Bitcoin transactions from attempts to re-spend coins that have already been spent elsewhere.
WHAT IS CLOUD MINING?
Cloud mining or cloud hashing enables users to purchase mining capacity of hardware in data centres.
Bitcoin cloud mining enables people to earn Bitcoins without managing hardware, software, electricity, bandwidth or other offline issues.
Then all Bitcoin mining is done remotely in the cloud. This enables the owners to not deal with any of the hassles usually encountered when mining Bitcoins such as electricity, hosting issues, heat, installation, or upkeep troubles.
Bitcoin mining is intentionally designed to be resource-intensive and difficult so that the number of blocks found each day by miners remains steady. Individual blocks must contain a proof of work to be considered valid. This proof of work is verified by other Bitcoin nodes each time they receive a block. Bitcoin uses the hashcash proof-of-work function.
The primary purpose of mining is to allow Bitcoin nodes to reach a secure, tamper-resistant consensus. Mining is also the mechanism used to introduce Bitcoins into the system: Miners are paid any transaction fees as well as a "subsidy" of newly created coins.
This both serves the purpose of disseminating new coins in a decentralized manner as well as motivating people to provide security for the system.
Bitcoin mining is so called because it resembles the mining of other commodities: it requires exertion and it slowly makes new currency available at a rate that resembles the rate at which commodities like gold are mined from the ground.
The aim of bitcoin—as envisaged by Satoshi Nakamoto, its elusive creator—is to provide a way to exchange tokens of value online without having to rely on centralised intermediaries, such as banks. Instead the necessary record-keeping is decentralised into a “blockchain”, an ever-expanding ledger that holds the transaction history of all bitcoins in circulation, and lives on the thousands of machines on the bitcoin network. But if there is no central authority, who decides which transactions are valid and should be added to the blockchain? And how is it possible to ensure that the system cannot be gamed, for example by spending the same bitcoin twice? The answer is mining.
Every ten minutes or so mining computers collect a few hundred pending bitcoin transactions (a “block”) and turn them into a mathematical puzzle. The first miner to find the solution announces it to others on the network. The other miners then check whether the sender of the funds has the right to spend the money, and whether the solution to the puzzle is correct. If enough of them grant their approval, the block is cryptographically added to the ledger and the miners move on to the next set of transactions (hence the term “blockchain”). The miner who found the solution gets 25 bitcoins as a reward, but only after another 99 blocks have been added to the ledger. All this gives miners an incentive to participate in the system and validate transactions. Forcing miners to solve puzzles in order to add to the ledger provides protection: to double-spend a bitcoin, digital bank-robbers would need to rewrite the blockchain, and to do that they would have to control more than half of the network’s puzzle-solving capacity. Such a “51% attack” would be prohibitively expensive: bitcoin miners now have 13,000 times more combined number-crunching power than the world’s 500 biggest supercomputers.