Documentary techniques include observational, reportage, reconstruction, and interviews. Observational involves following and observing a subject's life. Reportage tells news stories based on evidence. Reconstruction connects information to understand past events. Interviews involve face-to-face questioning. It is acceptable for documentaries to be subjective by following a particular story or perspective, but they should not be biased by only showing one side. Advertising techniques use repetition, rewards, slogans, taglines, guilt, aspirations, and sympathy to persuade viewers. Repetition emphasizes brands and slogans. Rewards offer prizes to attract interest. Slogans and taglines are catchy phrases. Guilt, aspirations, and sympathy appeal to emotions.