- [Instructor] Web fonts have provided
a significant contribution to the aesthetic functionality
and communication success of the web.
The modern web would not be where it is today
without the ability to display text using custom fonts.
However, web fonts are also a major performance hog
for several reasons.
First, web fonts require their own style sheets
or style declarations to work,
which adds to the CSS weight.
Second, web fonts require their own font files,
one file for each individual font weight or style.
If you use several styles of font,
think weights, italics, et cetera,
you need several font files,
and all of these files often live on external services,
like Google Fonts.
While web fonts make our texts more visually appealing,
they also cause some significant user experience problems
with weird names, like FOUT or flash of unstyled text,
or FOIT, flash of invisible text.
If you choose to use custom web fonts, and most projects do,
then web font optimization becomes an important part
of your performance plan.
So in this chapter, we'll take a deeper dive.