What Is Serif?
A serif is the small line or foot attached to the end of a letter's stroke. By extension, a serif typeface is one whose letters carry these finishing strokes. Serifs guide the eye along lines of text, which is why serif faces like Times and Garamond are traditional for long-form reading.
Serifs trace back to Roman stone carving, where chisel marks left small terminals at stroke ends. Printers carried the convention into movable type, and it dominated book typography for centuries.
Serif designs are grouped into styles — old-style, transitional, modern (Didone), and slab — each with different contrast and serif shapes. Choosing among them sets the historical and emotional tone of a design.