What does the acronym 'NSFW' stand for on Reddit?

On Reddit, NSFW stands for “Not Safe For Work.”

The label is an internet warning that content may be inappropriate to view in a workplace, school, public setting, or other environment where explicit or disturbing material could cause problems. On Reddit, an NSFW designation can apply to posts or communities containing nudity, sexual material, graphic violence, profanity, or other adult-oriented content.

The term became common in online communities during the early 2000s. It is a practical warning rather than a precise description of every item: one person may consider profanity NSFW, while another may reserve the label for sexual or graphic imagery. Reddit uses the designation both to warn users and to support content controls and filtering.

“Not Suitable For Work” is sometimes used as a near-equivalent phrase, which can make the acronym seem ambiguous. However, “Not Safe For Work” is the standard expansion and the canonical answer expected in a general trivia question. The contrasting label SFW means “Safe For Work,” while NSFL, or “Not Safe For Life,” warns of especially disturbing material.