Typography units are measurements used in the design of printed materials. The three most common typography units are ENS (3 letters), PICAS (5 letters), and EMS (3 letters). ENS stands for 'EN' and is a unit of measurement equal to half of an inch. PICAS stands for 'Picas and Points' and is a unit of measurement equal to 12 points. EMS stands for 'Em Square' and is a unit of measurement equal to the width of a capital letter M.