The curly bits on letters are called serifs. Apparently they make reading easier by providing minute signals to the brain that help identify letters more quickly.
The difference is not always that easy to see, but then you look at these
And you realise that the serifs really do help.
Viewfromtheside's Blog 
The Quick Brown Fox Jumps Over The Lazy Dog . . . with the help of a few serifs. 😉
well done
I have been arrested by the serif a time or two. Nothing curly about him. Went “straight ” to the pokey.
Oh dear Carl, that doesn’t sound too good!
So I see, small curl in huge lives. The Antanovs are also good for Arfica, big distances and sometimes not very good airport facilities
OK, I knew they were something to do with stylised writing, but now I understand… I think…
it’s stylised letters, not the content. interesting in the evolution of writing, how the little bits have been clues
What lovely curly bits!
they arewhen you look at handwriting samples
And here I thought those serifs just liked to show off. 😉
they do, and to aid and abet recognition and therefore comprehension
I shot the serif … but I didn’t shoot the deputy ….
are the punctuation marks the deputies?
I prefer sans serif – it’s strange, when I type into the box here it comes up in Ariel….that changes to (?) Times New Roman.