A bristle is a stiff hair or feather (natural or artificial), either on an animal, such as a pig, a plant, or on a tool such as a brush or broom.
Synthetic materials such as nylon are also used to make bristles in items such as brooms and sweepers.
The bristle brush and the scrub brush are common household cleaning tools, often used to remove dirt or grease from pots and pans.
[1] In cleaning applications, flagged bristles are suited for dry cleaning (due to picking up dust better than unflagged), and unflagged suited for wet cleaning (due to flagged ends becoming dirty and matted when wet).
One breed, the Tamworth pig, is endowed with a very dense bristle structure such that sunburn damage to skin is minimized.