+A **stain** is a discoloration that can be distinctly seen on a [Surface](/wiki/surface) or material, differing from its original [Color](/wiki/color). It often forms when a foreign substance penetrates and adheres, proving difficult to remove and sometimes leaving a lasting mark.
+## See also
+- [Dye](/wiki/dye)
+- [Cleaning](/wiki/cleaning)
+- [Pigment](/wiki/pigment)
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