Mining refers to the process of validating blocks of transactions so they can be added to the Bitcoin blockchain for which miners receive a reward of newly created bitcoin (BTC).
The process of mining new blocks by miners and adding them to the blockchain is how BTC transactions are confirmed and processed.
Approximately every ten minutes a new block is added to the blockchain, resulting in both the confirmation of transactions and the generation of new BTC. Currently, 6.25 BTC is generated with each new block which is awarded to the miner that found the block.
Miners are people that run specialised mining computers/infrastructure.
All miners compete to mine the next block by using their computing power to find a random number that make the block valid. Once a miner has found a solution, it sends his valid block to the network where each node verifies that the solution is valid. The miner is then rewarded with the newly-generated BTC. This is called the "block reward".
Today most of the miners are mining professionally in so-called mining farms. These farms host a lot of computers, utilising specially designed chips (ASICs).
