I was taught in junior high school English classes that, when listing three or more items in a sentence, you do not place a comma before the final conjuntion. To wit:
In my sack I have apples, oranges and peaches.
Lately, however, I’ve been seeing it done (specifically, in my Dungeons & Dragons rulebooks) with a comma:
In my sack I have apples, oranges, and peaches.
Is one way more correct than the other? Has there been a change in the relevant grammar rule in the 26 years since my 8th grade English class? Is it simply a matter of which stylebook the publisher uses? Or is it context that matters - prose vs. technical writing?
A comma before the conjunction just seems extraneous, unnecessary and redundant to me.