Tablet coating is used to improve the appearance and acceptability of tablets and to protect active ingredients from moisture or stomach acids. There are three main types of coatings: sugar coating for taste masking, film coating for protection and enteric coating to prevent dissolution in the stomach. Quality control tests on tablets include friability testing to ensure tablets can withstand damage from handling and dissolution testing to check that coatings dissolve properly. The document provides an overview of tablet coating processes and quality control tests used to evaluate coated tablets.