Yarn bombing or yarnbombing is a type of graffiti or street art that employs colorful displays of knitted or crocheted cloth rather than paint or chalk. Examples have been recorded as early as May 2004 in Den Helder, Netherlands. In the U.S., in 2005 Texas knitters used their leftover and unfinished knitting projects, but it has since spread worldwide. While yarn installations called yarn bombs or yarnstorms may last for years, they are considered non-permanent, and, unlike graffiti, can be easily removed if necessary. Nonetheless, the practice is still technically illegal, though it is not often prosecuted vigorously.

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