Serif
In typography, serifs are semi-structural details on the ends of some of the strokes that make up letters and symbols. A typeface with serifs is called a serif typeface (or serifed typeface). A typeface without serifs is called sans serif or sans-serif, from the French sans, meaning “without”. Some typography sources refer to sans-serif typefaces as "Grotesque" (in German "grotesk") or "Gothic", and serif typefaces as "Roman".
Serif fonts are widely used in traditional printed material such as books and newspapers. Many magazines employ sans serif typefaces, as some editors state that they are "cleaner", regardless of any impact on readability from the lack of serifs. Numerous studies have been done on the readability of serif vs. sans serif typefaces, without a consistent conclusion. Some studies indicate that serif typefaces may be more readable in print, but there is no consensus. Studies of on-screen use are also ambiguous, suggesting that low screen resolutions make serifs more difficult to discern, with a resulting erosion of readability compared to sans serif fonts.
Read more about Serif: Origins and Etymology, East Asian Analogues, Readability and Legibility, Classification