Mutualism (movement) is a way of working together between two or more people, companies, or organizations. It's about helping each other out by providing services or products for each other. A lot of times, a company that does one type of work might need another kind of service from a different company, so they might agree to help each other out. For example, one company might make trees and another might make paper, so they might agree to trade trees for paper so that they each get what they need. Mutualism helps everyone out by making sure that everyone has what they need.