Grit refers to the coarseness or fineness of the sandpaper. Lower grit numbers indicate coarser sandpaper, while higher grit numbers indicate finer sandpaper. Common grits range from 40 (very coarse) to 1200 (very fine).

Sandpaper comes with different backing materials, each with its own advantages. Paper backing is flexible and suitable for light sanding tasks, while cloth backing is more durable and tear-resistant, making it ideal for heavy-duty applications. Film backing provides superior resistance to moisture and heat, making it excellent for wet sanding and high-speed sanding.

Selecting the appropriate sandpaper depends on the materials being sanded, the desired surface finish, and the sanding method. Coarser sandpaper (low grit) is ideal for removing material quickly and smoothing rough surfaces. Finer sandpaper (high grit) creates a smoother finish and is suitable for finer sanding or finishing work.

Dry sandpaper is used for sanding without lubrication, while wet sandpaper is designed for sanding with water or other liquids. Wet sanding produces a finer finish and reduces dust, making it suitable for delicate surfaces or precision sanding tasks.