When parts of the image (typically graphic or sensitive contents such as sexual organs, gore, or offensive symbolism) were obscured, typically to comply with censorship laws.
On Danbooru, this typically encompasses various Japanese pornographic materials that were censored as a result of the Japanese law. Techniques that prevent viewing sexual parts, usually vaginas, penises and dildos but occasionally nipples. Note that the anus is not usually considered a sexual part in Japanese censorship.
Common forms include mosaics, black bars, mysterious white lights, inverted colors, shaded bars, and the infamous invisible penis. Tentacles or phallic objects are commonly used to resemble genitals and generally don't need to be censored, though the point of intercourse with a vagina does.
For obstructions that are internal to the picture, like a lock of hair that just happens to cover the genitals, use the tag convenient censoring instead of censored.
