Each letter of the modern western
alphabet has a width determined by Its
Inherent structure. Because of this,
letters are assembled Into words with
what Is known as differential spacing.
This Is the spacing of each letter
according to Its Individual width.
space or M/5; slx-to-em, also known as
hair space or M/6.
An em-quad Is equal to the square of the
point size of a letterform. The em Is the
widest single spacing unit of a typeface.
An en Is equal to half the em of a
typeface. The en Is also known as two-to-
em which means two of these units equal
one em. Other Increments include Three-
to-em, also known as thick space or M/3;
four-to-em, also known as middle space
or M/4; flve-to-em, also known as thin
s 1 p 1 a I c i n g
differential spacing mono spacing
Back in the day, we had to enforce certain laws in keeping
characters in line. If a single character slipped in any
direction, it was sent to ISO for rehabilitation.
The body of text that we found has considerable spacing
problems, so we send it to the Forensics lab for repair.
1 2 3 4 I 5 6 7 8 9 10 11 12 13 14 15 16 17 18
36 points 18 points
j \Й»? I it
In 1887, Tolbert Lanston invented the unit
system of measure In order to allow greater
precision In adjusting the spacing between
letters and words. Like the em-quad, the unit
Is a relative width system that changes In
proportion to the typeface and Its point size.
The unit Is determined by the em-quad
of a typeface. The unit value of a specific
typeface was originally established by
dividing the em-quad Into 18 vertical
segments. Since the onset of digitization,
units In Increments of 16, 36, 72 and
even 1000 are used.
The letter and Its surrounding space
always occupies a whole number of units.