The amount of credit money which the banking system as a whole can create, is determined by the policies of the Federal Reserve, the private banking cartel which has been given power over money in the United States. When you deposit your paycheck in a commercial bank the bank is acting as a depository. This money is then available for you to write checks against. But, the money which you deposited had to begin somewhere. The important thing to understand is the nature of that beginning.
Banks create money by making loans.
Here's the way it works. Company XYZ goes to a commercial bank and receives a loan to expand its business. The bank simply credits the account of Company XYZ for the amount of the loan. In exchange for the note or security, the lending or investing institution credits the depositor's account or gives a check that can be deposited at yet another depository institution. In this case, no one else loses a deposit.