Wiley Typographic Web Design: How to Think Like a Typographer in HTML and CSS 978-1-1199-7687-5 User Manual

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978-1-1199-7687-5
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Text is meant to be read. If it feels diffi
  cult to read, 
people won’t want to read it. How easily text can 
be read on the web depends on how type is used 
on the screen. One factor that aff ects readability, 
and a great place to start, is choosing a legible font. 
What Makes a Font Legible?
When we read, we don’t see individual letters; we 
see (and read) the shapes of the words. These 
shapes are created primarily by two elements: the 
strokes of the letters and the spaces in and around 
the letters. If we lose either of these elements, 
legibility is compromised.
Did you ever try to read a poor photocopy of a 
photocopy of a photocopy? Experience tells you 
that type becomes harder to read with each gener-
ation of copying. Why does this happen? 
Sometimes, multiple-generation photocopies 
make the text lighter. Thinner strokes start to 
disappear, leaving only parts of letters and 
compromising the word shapes. At other times, 
multiple-generation photocopies make the strokes 
in the text thicker. The spaces in and around the 
letters start to disappear. Either way, when strokes 
CHAPTER 
1
Anatomy and Legibility: Is the Font Easy to Read?
or spaces get lost, the legibility of the font 
changes, and reading becomes more diffi
  cult.
Web typographers need to pay particular attention 
to the strokes and spaces in a font because of 
screen resolution. Macintosh screens are 72 pixels 
per inch, or ppi, and Windows screens are 96 ppi. 
A font set at 12px (pixels) will appear approxi-
mately 
1
6
 inch tall on a Mac screen and less than 
1
8
 
inch tall on a Windows screen. In either case, the 
screen will have (at most) 12px by 12px to render 
a letter. Thin strokes and small spaces in letter-
forms start to disappear, and as in the photocopy 
example, the text will be harder to read.
You’ll often hear that “simple” fonts are better for 
the screen because of the resolution issues. That’s 
a good rule of thumb, but it’s not quite enough.
Comparing Georgia and Helvetica
Helvetica is simpler and cleaner than Georgia, but 
Georgia is easier to read (Figure 1.1). Text set in 
Helvetica 12/18 (12px text with an 18px line 
height) is readable onscreen. Text set in Georgia 
12/18, however, is more readable, even though it 
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