Today, all global economic systems use currencies issued by internationally accepted monetary systems. In order to participate in these economies you must first exchange your time for money.
This exchange is done by a work contract between you and a person or organization that pays you for the market value of your time, or a social contract between you and a governing entity that pays you for your value as a member of its purview.
The goal of a well-functioning society is to maintain a healthy dialectic between these two types of exchanges in order to maximize the combined benefits they can bring to its members, namely, prosperity through peace. Unfortunately, the goal often defaults to control and containment in order to increase profit through pacification.