Microexpressions are brief, involuntary facial expressions that occur in response to emotions. They typically last only a fraction of a second and can reveal a person's true feelings, even if they are trying to hide them. These expressions are universal and can be observed across different cultures, making them a valuable tool in understanding human emotions. Psychologists and researchers, such as Paul Ekman, have studied microexpressions to improve emotional intelligence and communication skills. By recognizing these fleeting expressions, individuals can gain insights into others' emotional states, enhancing interpersonal interactions in various settings, including therapy, negotiations, and law enforcement.