Opinion leadership refers to the process where one person informally influences the attitudes or actions of others. Opinion leaders are knowledgeable about specific products and share this knowledge with others who seek their advice. They tend to be early adopters of new products, self-confident, and belong to the same social class as potential consumers. There are two theories that explain how information flows through interpersonal channels: the two-step flow theory where opinion leaders influence other consumers; and the multi-step flow theory where information passes through multiple people. Marketers identify key opinion leaders for different product categories and target promotional strategies accordingly, such as encouraging word-of-mouth from hairstylists for hair products or pharmacists for healthcare items.