This is one of the first things you'll learn studying Macroeconomics. Any introductory book on that topic will teach you about the concept. In general, you can

This is one of the first things you'll learn studying Macroeconomics. Any introductory book on that topic will teach you about the concept. In general, you can look for information pertaining to "How banks create money," which refers to your $100 deposit turning into $1000 after it completes the ownership ladder. If you're still in college and have the opportunity to take some electives, I highly recommend Micro and Macroecon.