The em is a unit of measurement in the printing and typesetting industry. Its primary function is to indicate the height of typefaces expressed as points; one em equals one point size of any given font.
For centuries, printing and typesetting industry professionals have relied upon ems as an integral unit of measurement. Emas can define leading (the space between lines of text), measure (the width of a text column), margin sizes, and lead length. Furthermore, this measurement can indicate various design elements such as rule line width or photo margin sizes – with any of these elements often having dimensions specified using an em.
While ems still play an integral part in printing and typesetting industries, their importance in digital design has significantly decreased as pixels provide more accurate measurements than ems.
An Em is a measure of text column width. Traditionally defined as the width of the capital M in any typeface and size used, digital typefaces allow for digital Ems that can be expressed in pixels, points, or percentages of typeface width.
The Em is an essential unit of measurement in printing, as it ensures consistent margins and column widths. When setting type, its width must be considered so that text fits comfortably on each page and margins will be appropriate.
Printing with an em is beneficial because it serves as a measure for typography. Printing uses it to specify column width and align text properly across a page; additionally, it measures typeface sizes and character spacing between characters. Printers who understand and utilize this measurement can produce high-quality print products that are visually appealing and easily read.