Not safe for work (NSFW) is Internet slang or shorthand used to mark links to content, videos, or website pages the viewer may not wish to be seen viewing in a public, formal or controlled environment. The marked content may contain graphic violence, pornography, profanity, nudity, slurs or other potentially disturbing subject matter. Environments that may be problematic include workplaces, schools, and family settings.^[1][2] NSFW has particular relevance for people trying to make personal use of the Internet at workplaces or schools which have policies prohibiting access to sexual and graphic subject matter.^[3] Conversely, safe for work (SFW) is used for links that do not contain such material,^[4] especially where the title might otherwise lead people to think that content is NSFW.^[5]

The similar expression not safe for life (NSFL) is also used, referring to content which is so nauseating or disturbing that it might be emotionally scarring to view. Links marked NSFL may contain fetish pornography, gore or murder.^[6]

Some websites, such as Reddit and OnlyFans give users the option to designate their content as NSFW in order to warn others of its inappropriate nature.^[7]