From a management viewpoint sales is thought of as a part of marketing, although the skills required are different. Sales often forms a separate grouping in a corporate structure, employing separate specialist operatives known as salesperson. Selling is considered by many to be a sort of persuading "art". Contrary to popular belief, the methodological approach of selling refers to a systematic process of repetitive and measurable milestones, by which a salesperson relates his or her offering of a product or service in return enabling the buyer to achieve their goal in an economic way. While the sales process refers to a systematic process of repetitive and measurable milestones, the definition of the selling is somewhat ambiguous due to the close nature of advertising, promotion, public relations, and direct marketing.