The point is the smallest whole unit of measure in typography. It is used for measuring font size, leading, and other minute items on a printed page. Different points have been used since the 18th century, with measures varying from 0.18 to 0.4 millimeters. Following the advent of desktop publishing in the 1980s and '90s, the importance of digital printing supplanted the letterpress printing systems around the world and established the DTP point as the de facto standard. This measures of the international inch (about 0.353 mm) and, as with earlier American points, is considered of a pica.