Serif is a small decorative line attached to the end of every letter or symbol. It makes each letter complete in itself and distinct from the rest, hence boosting our letter recognition which gives the reading a desired smoothness. It has a flowing feature, which makes it less tiring for the eye to continually read larger texts at a stretch. Serif fonts are most commonly used in printed texts – newspapers, books, magazines. The ‘Times New Roman’ is an example of Serif typeface.
Sans serif is a font type which is ‘sans’ (without) ‘serif’. It does not have those small flourishing lines attached to the letter end to make it look fancy. This typeface is contemporary and most commonly used in web typography. Sans serif is a simple font, thus making reading easier. The ‘Futura’ typeface is an example of Sans serif typeface.
So, serif in the books and ‘sans’ in the internet makes reading interesting and engaging for all kinds of readers.