We each have a set of unwritten rules that we carry with us about how people should think and act. These unwritten rules are different depending on culture, background, beliefs, values and experiences. Differences in these unwritten rules lead to misunderstandings and thus, conflict.
For example, a man may have been taught by his parents that it is very important to meet deadlines and he makes sure to do so at work. If his boss and other employees do not follow the same unwritten rule and are unconcerned about meeting specific deadlines, the man may become frustrated, with a potential for the development of conflict. The hidden idiosyncratic nature of unwritten rules is a key source of misunderstanding and conflict.
We are each distinct individuals with varying beliefs, values, and perspectives. With these differences come misunderstandings that can be diffused through effective communication.