In writing and typography, a "serif" refers to a small decorative line or stroke that is added to the ends of a larger stroke in a letter or symbol within a particular font. Serif fonts have these embellishments at the ends of their letters, which can give them a more traditional and formal appearance.
Common examples of serif fonts include Times New Roman, Garamond, and Georgia. These fonts are often used in printed materials, such as books and newspapers, because the serifs can help guide the reader's eye along the lines of text, potentially improving readability.
In contrast, "sans-serif" fonts, such as Arial and Helvetica, do not have these decorative lines and tend to have a more modern and clean appearance. The choice between serif and sans-serif fonts can significantly affect the tone and readability of written content.