Commas and punctuation

There were a few questions last night about when to use commas. Click here to go to UVic's webpage on commas.

On page 222 (unit 111) of our grammar book, there are sentences such as:

"The car stopped, and the driver got out."
"I bought a newspaper, but I didn't read it."

In general, the rule is that you use a comma before 'and', 'but', 'or' to join two independent clauses. BUT if the clauses are both short, then you don't need the comma (see rule 12 at http://www.grammarbook.com/punctuation/commas.asp).

"The car stopped and the driver got out."
"I bought a newspaper but I didn't read it."

You should always use a comma before the conjunction 'so'.

"She wasn't feeling well yesterday, so she stayed in bed."
"I lost my purse, so I can't buy anything today."