EMS stands for 'EM' widths, which are a unit of measurement used in typography. Typography widths refer to the width of characters and spaces in a typeface, and EMS is one of the most commonly used units of measurement. EMS is equal to the point size of the typeface, meaning that one EM is equal to the width of one point in the typeface. EMS is used to measure the width of characters, spaces, and other elements in a typeface, allowing designers to create consistent and balanced typography.