Font Classifications

Old style- a style of font developed by Renaissance typographers to replace the Blackletter style of type. Based on ancient Roman inscriptions, these fonts are generally characterized by low contrast between thick and thin strokes, bracketed serifs, and a left-leaning axis or stress. There are two groups of Old Style typefaces: Venetian (Renaissance) and Garalde (Baroque).
Examples: Garamond, Centaur, Goudy Oldstyle, Century Oldstyle, Palatino, Sabon

Transitional- the Old Style of type of the 16th and 17th centuries evolved into a style known as Transitional. The primary characteristics of Transitional type are medium contrast between thick and thin strokes, less left-inclined stress than earlier Old Style faces, and a triangular or flat tip where diagonal strokes meet (such the base of a W).
Examples: Baskerville, Times New Roman, Bell, Perpetua

Modern- a style of typeface developed in the late 18th century that continued through much of the 19th century. Characterized by high contrast between thick and thin strokes and flat serifs, Modern fonts are harder to read than previous and later typestyles.
Examples: Bodoni, Didot, Bernhard Modern Roman

Slab Serif- A Slab Serif is a type of serif font that evolved from the Modern style. The serifs are square and larger, bolder than serifs of previous typestyles. Considered a sub-classification of Modern
Examples: Clarendon, American Typewriter, Rockwell

Sans Serif- type which does not have serifs. Within sans serif there are five main classifications: Grotesque, Neo-Grotesque, Geometric, Humanist, and Informal. Typefaces within each classification usually share similarities in stroke thickness, weight, and the shapes of certain letterforms.
Examples: Arial, Helvetica, Verdana, Futura, Univers, and Franklin Gothic

Serif - a font with the little extra stroke found at the end of main vertical and horizontal strokes of some letterforms. In some cases serifs may aid in the readability of a typeface. Serif refers, in general, to any style of type that has serifs.