Filter paper is a semi-permeable paper barrier that is put perpendicular to the passage of liquids or air. It separates tiny solid particles from liquids or gasses.

Filter paper offers a variety of qualities. The key factors include wet strength, porosity, particle retention, volumetric flow rate, compatibility, efficiency, and capacity.

There are two methods of filtering using paper: volume and surface. Volume filtration traps particles in the bulk of the filter paper. Surface filtration captures particles on the paper surface. Filter paper is widely used because a little piece of filter paper may absorb a large volume of liquid.