Many tests and research have shown that the eyes of an average reader actually scans across the upper half of the overall shape of words. And the more clues there are to be seen, the easier your brain will be able to recognise the words. So the preference is not just a matter of a personal taste or an appropriate style.

Try the test below for yourself, or create a similar one in English, or even better: in your own language, because that's what your brain is used to read best.

Fonts with serifs simply offer more elements to distinguish the shape of the word, while quickly glancing through lines of text. That's why most books and lengthy texts are preferable formatted in serif fonts.

Of course, many other aspects can deteriorate the legibility of a text, like its width, the line height, or just a plain ugly serif font. And the difference really only counts when it's about longer texts. For just a heading, one sentence, or even a whole paragraph, the benefit is almost next to none, since your eyes and brain will first have to accommodate to the text formatting anyway.

Oorspronkelijk geplaatst op Quora: When should you use serif vs sans-serif fonts in web design?"