Blotting paper is a special kind of thick, absorbent paper designed to soak up excess liquid ink. Before ballpoint pens became common, people wrote with fountain pens that used wet ink, which could smudge or create puddles on the page if you weren't careful. Writers would press a piece of blotting paper against fresh ink to absorb the extra liquid without smearing the words, helping the writing dry faster and look neater.

The paper works through tiny spaces in its fibers that draw in liquid, similar to how a paper towel soaks up spilled juice. Unlike regular paper, blotting paper has no coating or sizing (a substance that makes regular paper smooth), so it's especially thirsty for liquids.

Though fountain pens are less common today, blotting paper still has uses. Scientists use it in laboratories to absorb liquids in experiments. Artists sometimes use it to create interesting effects with ink or watercolors. Some people even use blotting paper to absorb excess oil from their skin.

You might encounter blotting paper in old-fashioned desk sets, where it often came in decorative holders called blotters. These desk blotters sometimes had handles and rocking mechanisms that made pressing the paper onto wet ink easier and more elegant.