where did ``xxx" quotes come from?

Ive seen the quoting style of using 2 backticks (``) in front with regular double quotes on the end of something being quoted. Im assuming this is from K&R, but does anyone know where that originates from and if there is any practical reason for it?

>>1
A simple Google would've yielded http://www.cl.cam.ac.uk/~mgk25/ucs/quotes.html.

Summary: Faggot quotes considered harmful.