Because YouTube keeps changing policies on the types of content that is eligible to be monetized with advertising, many content creators are concerned about these frequent changes. YouTube policies restrict certain forms of content from being included in videos being monetized with advertising. This includes videos containing violence, strong language, sexual content, "controversial or sensitive subjects and events, including subjects related to war, political conflicts, natural disasters and tragedies, even if graphic imagery is not shown" (unless the content is "usually newsworthy or comedic and the creator's intent is to inform or entertain"), and videos whose user comments contain "inappropriate" content. However, it is not clear what is the boundaries for what YouTube's policies specifically accept and do not accept. Some content creators also say that YouTube's policies also change too often. For example, on January 16, 2018, the requirement for a channel to be monetized is to get 4,000 hours of watchtime within the past 12 months and at least 1,000 subscribers. Although YouTube's intent was to avoid monetizing videos of channels seen as controversial, people criticize that this move greatly harms smaller YouTube channels.