Typesetting units are used in the printing industry to measure the size of text and other elements on a page. The three most common typesetting units are ENS (3 letters), PICAS (5 letters), and EMS (3 letters). ENS stands for 'em-sized units' and is equal to the width of the letter 'M' in a particular font. PICAS stands for 'pica-sized units' and is equal to 12 points, or 1/6 of an inch. EMS stands for 'em-sized units' and is equal to the height of the letter 'X' in a particular font.