A slab serif font is a serif font where the serif is squared off, giving the font a blocky, sturdy appearance as opposed to the more refined look of a traditional serif. Slab serifs tend to have less contrast overall than other serifs, which contributes to their heavy, often dramatic appearance. Slab serif fonts are typically used where a display font is required, such as book covers, posters, advertisements, logotypes, or as complimentary fonts in a broader type system. Popular slab serif fonts include Rockwell, Clarendon, Serifa, Courier, and Memphis.
Slab serif fonts are typically used for display purposes—headlines, posters, billboards, logos, and other situations where bold type can stand out. Their sturdy structure and often exaggerated design accents are excellent at grabbing attention. These same features make many slab serifs a less than ideal choice for long-form copy like magazine articles, though there are slab serif fonts that work well in blurbs and text of moderate length.
The difference between a serif font and a slab serif font lies in the serif itself. On a traditional serif font, the serif is usually angular, with either a curved or diagonal edge leading to a pointed end of the serif. On a slab serif font, the serif is almost always squared off, giving the letterform a blockier appearance. The result is that regular serif fonts tend to have a more delicate or refined look, while slab serif fonts are heavier and more commanding.