This document discusses perception and related concepts. It defines perception as how people understand the world through their senses and cognitive processes. It describes perception as having three dimensions: understanding, view, and action. It also discusses two types of perception: positive and negative. The document outlines several principles and factors that influence perception, including that perception is relative, selective, and has arrangement. It explains the three stages of perception as selection, organization, and interpretation. Finally, it discusses four factors and two sets of factors that can influence an individual's perception.