Miners are the Bankers of Bitcoin and make the system work. However, unlike Federal Reserve which is a centralized system, the mining system of Bitcoin is a decentrelized system.
Source World Bitcoin Network
The job of the miners are to create new bitcoins which are rewarded to them when they maintain the Bitcoin Blockchain by adding transactions. But for now, every day that goes by it becomes harder to solve the equation, so you need more and more computing power!
The Bitcoin Network system might be the worlds largest computer network systems.
Understanding why Satoshi needed mining is fundamental to understanding decentralization and bitcoin. The mining of Bitcoin’s is limited to 21 million Bitcoins as scarcity is key with any Monetary system.