Bitcoin mining is a process that is performed using special computers. These computers are designed to verify transactions and add them to the public ledger, known as the blockchain.
In order to be rewarded with Bitcoin, miners must confirm these transactions. .
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.
GPUs are much more efficient at Bitcoin mining than CPUs. A GTX 1080 can mine about 1 Bitcoin per month.