How does a serif font differ from a sans serif font?

'Arial Font' is an example of 'sans serif'. 'Sans' is french for 'without'. The serif is for the added bits that are attached to letters. So the text I am currently writing this answer in is 'Sans Serif'.

This was to be the books beginnings... - sans serif

This was to be the books beginnings - serif

An example of a serif font is Times New Roman. Compare the two sentences above. There are differences in the letter's 'T', 'b' and 'k'. They have added lines on the tops of the lines that make up the letters. These are called 'serif's.

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The above answer FAILS because the webpage translates both sentences into a san serif, so you can't see the difference.

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Serifs are the little feef and hands added to the end of all the lines in an individual letter, originally added to prevent ink from running and causing blobs on the ends on each line.