Ink stains are marks left by liquid ink on various surfaces, such as paper, fabric, or skin. They can occur from spilled ink, leaking pens, or accidental contact with inked materials. The color and permanence of the stain depend on the type of ink used, with some inks being water-soluble and easier to remove than others. Removing ink stains can be challenging, as they often set quickly. Common methods for cleaning include using rubbing alcohol, vinegar, or commercial stain removers. It's important to treat the stain as soon as possible to increase the chances of successful removal and prevent permanent damage to the affected surface.