What do the different sandpaper grits mean?

Choose the Right Sandpaper Grit 

Selecting the correct grit is essential for achieving the desired finish. Sandpaper grits are numbered from course to fine. lower numbers are coarse grit, while higher numbers indicate finer grit. 

• Coarse Grit (40–60): Removes heavy layers of paint, varnish, or material quickly. 
• Medium Grit (80–120): Good for leveling uneven surfaces and smooths out imperfections. 
• Fine Grit (150–220): Great for preparing surfaces for painting or staining with a clean finish. 
• Very Fine Grit (240+):  Best used for an ultra-smooth surface for final finishing work.