Money is a side effect of specialization. In a specialized society, most of the things you need, you can’t make for yourself. If you want a potato or a pencil or a place to live, you have to get it from someone else.
How do you get the person who grows the potatoes to give you some? By giving him something he wants in return. But you can’t get very far by trading things directly with the people who need them. If you make violins, and none of the local farmers wants one, how will you eat?
The solution societies find, as they get more specialized, is to make the trade into a two-step process. Instead of trading violins directly for potatoes, you trade violins for, say, silver, which you can then trade again for anything else you need. The intermediate stuff— the medium of exchange— can be anything that’s rare and portable. Historically metals have been the most common, but recently we’ve been using a medium of exchange, called the dollar, that doesn’t physically exist. It works as a medium of exchange, however, because its rarity is guaranteed by the U.S. Government.
The advantage of a medium of exchange is that it makes trade work. The disadvantage is that it tends to obscure what trade really means. People think that what a business does is make money. But money is just the intermediate stage— just a shorthand— for whatever people want. What most businesses really do is make wealth. They do something people want.