The problem of social cost happens when our actions have negative impacts on other people. This can happen when something that one person does causes other people to have problems - even if that person didn't mean to cause them. For example, if someone drives a car very loudly in their neighborhood, the loud noises can be really annoying and disruptive to everyone who lives there. The person who drives the car doesn't realize their actions have caused a problem, but everyone else can hear it and know it was caused by them. Social cost is the idea that when one person takes an action, they should think of how it will affect other people.