Typography is fundamental to good design, branding, readability, and accessibility. Web fonts enable all of the above and more: the text is selectable, searchable, zoomable, and high-DPI friendly, providing consistent and sharp text rendering regardless of the screen size and resolution. WebFonts are critical to good design, UX, and performance.
Web font optimization is a critical piece of the overall performance strategy. Each font is an additional resource, and some fonts may block rendering of the text, but just because the page is using WebFonts doesn't mean that it has to render slower. On the contrary, optimized fonts, combined with a judicious strategy for how they are loaded and applied on the page, can help reduce the total page size and improve page rendering times.
Anatomy of a web font
A web font is a collection of glyphs, and each glyph is a vector shape that describes a letter or symbol. As a result, two simple variables determine the size of a particular font file: the complexity of the vector paths of each glyph and the number of glyphs in a particular font. For example, Open Sans, which is one of the most popular WebFonts, contains 897 glyphs, which include Latin, Greek, and Cyrillic characters.