outsource part or all of the work to specialists such as advertising agencies, creative design teams, web designers, media buyers, events management specialists or other relevant service providers. Another option is for a company to carry out most or all of the advertising functions within the marketing department in what is known as an in-house agency. By definition, an in-house agency is "an advertising organization that is owned and operated by the corporation it serves". Its mission is to provide advertising services in support of its parent company's business and marketing objectives. Well-known brands that currently use in-house agencies include Google, Calvin Klein, Adobe, Dell, IBM, Kraft, Marriott and Wendy's. Both in-house agencies and outsourcing models have their own advantages and disadvantages. Outsourcing to an external agency allows marketers to obtain highly specialised strategic, research and planning skills, access to top creative talent and provides an independent perspective on marketing or advertising problems. In-house agencies deliver cost advantages, time efficiencies and afford marketers greater control over the advertising effort. In addition, personnel who work within an in-house agency gain considerable creative experience which stays within the company. Recent trends suggest that the number of in-house agencies is rising. Whether a company chooses to outsource advertising functions to an external agency or carry them out within the marketing department, marketers need a rich understanding of advertising principles in order to prepare effective advertising plans, brief relevant agencies about their needs and expectations or develop their own creative solutions to marketing problems. Advertising's role in the promotional mix The promotional mix refers to the specific combination of promotional methods used for a brand, product or family of products. Advertising is best treated as a multiplier that can leverage other elements of the promotional mix and marketing program.<ref>Jones, J.P., How Advertising Works: The Role of Research, Thousand Oaks, CA,1998, pp 25-30</ref> Therefore, advertising must be considered as part of a broader marketing and promotional program. The promotional mix includes a variety of tools such as: Advertising: messages paid for by those who send them and intended to inform or influence people who receive them Branded entertainment: the dedicated production of content designed to display corporate or branded messages in an entertaining format Public relations (PR): the practice of maintaining goodwill between an organisation and its publics Personal selling: face-to-face selling in which a seller attempts to persuade a buyer to make a purchase.