The document defines customers and categorizes them in different ways. Customers are defined as individuals or companies that engage in commercial transactions but do not perform the operations themselves. Customers can be categorized according to their place in the distribution chain as wholesalers, retailers, or final customers. They can also be categorized based on their relationship to products as impulsive, reflective, or emotional customers and by their purchase frequency as potential, loyal, casual, or prescribing customers. Finally, customers can be analyzed by their purchase volume, with some customers representing the largest percentage of total purchases and others representing smaller amounts.