Mining is a distributed consensus system which confirms transactions that have been completed and are waiting to be included in the block chain. The basic idea behind the mining process is to prevent fraud. The blocks in which the Bitcoin
transactions are stored has a capacity to store 1 megabyte of data and it is the miners that must confirm the genuineness of the transactions that are stored in the block. It is only when they do it, they earn bitcoins as a reward. Each block carries a value of 25 bitcoins. New bitcoins are generated into circulation only once a block is completed.
By confirming the authenticity of a transaction, It enforces a chronological sequence in the block chain. This protects the objectivity of the network, prevents older blocks and transactions from being tampered, matches the state of a system across different computers and eliminates the risk of blocks from being modified as any modification in the previous transaction will result in the subsequent blocks becoming invalid.
Since the transactions recorded by the miners are in public, it prevents any individual from adding new blocks in the chain easily. This way, individuals do not have any possibility of gaining control on what is added in the block chain.