Cryptocurrency mining is the process by which transactions for a cryptocurrency are verified and added to the blockchain digital ledger (a chronologically-ordered, time-stamped transaction ledger).
Cryptocurrency mining is verifying transactions on a blockchain ledger. Anyone with access to the internet and suitable hardware can participate in mining. The participant who first solves the problem gets to place the next block on the blockchain and claim the rewards. The rewards are transaction fees (from the transactions in the block) as well as the newly released cryptocurrency e.g. Bitcoins.