What's the difference between a serif and a sans-serif font?
Serif fonts (Times New Roman, Georgia) have small lines or 'feet' at the end of letterstrokes; they feel traditional and formal. Sans-serif fonts (Arial, Helvetica) are clean and modern with no serifs. Serifs actually improve readability in printed books, but on screens, sans-serifs are often clearer—this is why most websites use sans-serif body text.
