In typography, certain fonts will have a blunt and angular or rounded line at the end of a larger stroke: these are called slab serif fonts.
Zilla Slab is a contemporary slab serif and Mozilla's core typeface, used throughout their designs.
Slab serif fonts are varied in genre: more bold, heavy, and extreme slab serifs are perfect for grabbing attention on posters, while monospaced slab serifs are ideal for use in computer programming.
Slab serif fonts were typically used in typewriters, most notably Courier typewriters. The Courier typeface by Howard “Bud” Kettler has been adapted into the ubiquitous font seen on most computers today.
There are many subgroups of slab serif fonts, including Antique, Clarendon, Italienne, and Geometric models, and Typewriter typefaces. Typewriter slab serifs are named for their use in strike-on typewriting.
Slab serifs have incredible variety: Rokkitt draws inspiration from early slab serifs, Josefin Slab is a clean geometric Scandinavian style, and Roboto slab is mechanical with round, readable curves.