Binary oppositions are pairs of concepts that are opposite in meaning, such as good/bad, weak/strong, and security/insecurity. In a narrative, binary oppositions help establish relationships between characters, such as who is good or bad. They also help define concepts by their opposition to another - we understand "weak" by its contrast to "strong." Horror films commonly use binary oppositions like good/evil, sane/insane, and human/supernatural to drive their plots. Harry Potter relies on the opposition of Harry as the good guy and Voldemort as the bad guy wanted him dead. Pictures can represent binary oppositions to audiences clearly, such as good versus bad.