1. On the way over, we ate and drank.
   On the way over we ate and drank.
2. On the way over, we ate, we drank.
   On the way over we ate, and drank.

A comma splice happens when you place a comma (instead of a period or a semicolon) in between two complete sentences with no conjunction separating them.

1. A complete sentence
   A group of words that refers to nothing
2. A compound sentence containing "and," "but" or "or"
   A phrase that describes a noun

An independent clause is one that contains a subject and a predicate -- it's a complete sentence that can stand on its own.

1. Those words are the most important component of the sentence.
   Those words can be removed without changing the meaning of the sentence.
2. Those words cannot be removed without changing the meaning of the sentence.
   The reader should pause before and after the words in between the commas.

Commas typically indicate that what follows or fits between them is not essential to the meaning of the sentence.

1. An acronym
   A predicate that doesn't make sense
2. A clause that begins with "however"
   A group of words that is essential to the meaning of the sentence

Also called an "essential clause," a restrictive clause is one that is crucial to conveying the complete meaning of the sentence. It is not surrounded by commas.

1. In school, the children sang, read, and counted.
   In school, the children sang read and counted.
2. In school, the children, sang read and counted.
   In school, the children sang, read and counted.

The Oxford comma, sometimes called the Harvard comma or serial comma, is the comma that precedes the final item in a list.

1. 1 January, 2012
   1, January, 2012
2. 1 January 2012
   January 1 2012

In Europe and elsewhere, the date is written with the day first, then the month and then the year, with no commas.

1. Never
   Only when it starts a sentence
2. Any time it precedes a list
   Only when it's followed by four or more list items

The phrase "such as," which introduces examples, should never be followed by a comma. The same goes for "including."

1. Nowhere
   After it
2. Before it
   Before and after it

The word "which" introduces a descriptive clause that is nonrestrictive (nonessential), and nonrestrictive phrases take a preceding comma.

1. The store, which sells soap, opens at 10 a.m.
   The soap store opens at 10 a.m.
2. The soap store, and the art store, open at 10 a.m.
   The store that sells soap opens at 10 a.m.

A restrictive clause describes a preceding noun and has no commas, since it cannot be removed from the sentence without affecting the meaning (there may be other stores in the area, and we're talking specifically about the one that sells soap).

1. Yes
   No
2. Only when the name is male
   Only when it ends a sentence

While preceding a name suffix with a comma (Sammy Davis, Jr.) used to be common practice, it has recently fallen out of favor. Now, there's no comma separating the name from the essential suffix.