This document discusses media regulation and theories about how media can influence audiences. It begins by introducing several theories about media effects, such as the hypodermic needle theory, cultivation theory, and desensitization theory. It then discusses why regulating the media is important, such as limiting corporate power and protecting vulnerable groups like children. The document uses the example of a teenager who took her own life after becoming immersed in online content depicting self-harm. It concludes by explaining how different types of media are classified or censored in the UK, such as the British Board of Film Classification ratings system.