What is bitcoin mining?
Mining is the process of spending computation power to secure Bitcoin transactions against reversal and introducing new Bitcoins to the system. Technically speaking, mining is the calculation of a hash of the block header, which includes among other things a reference to the previous block, a hash of a set of transactions and a nonce (an arbitrary number used just once for authentication purposes).
Bitcoin mining is the process of verifying bitcoin transactions and recording them in the public blockchain ledger. In blockchain, the transactions are verified by bitcoin users, so basically the transactions have to be verified by the participants of the network. Those who have the required hardware and computing power are called miners.