Between items in a series:
The experience demanded blood, sweat, and tears.
Between coordinate adjectives:
We listened to an absorbing, frightening account of the event.
Before coordinating conjunctions joining ind. clauses:
Congress passed the bill by a wide margin, and the president signed it into law.
Around Parenthetical elements:
The invention, the first in a series during that decade, completely changed people’s lives.
After fairly long phrases or clauses preceding the main clauses of sentences:
After carefully studying all the available historical documents and persons writnngs
scholars could come to no definite conclusion.
1) Use commas between items in a series:
When I get nervous I sweat, tremble, and puke.
2) Use between coordinate adjectives:
When this happens, the entire world looks like green, mossy, lichen-covered tombstones.
3) Use commas before coordinating conjunctions joining independent clauses:
It's then that I wish I had listened to my mother, and I know you're just dying to know what she said.
4) Use around parenthetical elements:
She would put down the spoon she was mixing her bread dough with, that funky old thing she'd found at the thrift shop, and look at me with her serious eyes and say....
5) Use after fairly long phrases or clauses preceding the main clauses of sentences:
"When you're on stage and can't think of anything besides puking because your nerves are making you weak in the knees, just remember that old trick and picture your audience in their b.v.d.'s."
From The Bedford Handbook: (351): Use a comma after an introductory clause or phrase. The most common introductory word groups are clauses and phrases functioning as adverbs. Such word groups usually tell when, where, how, why, or under what conditions the main action of the sentence occurred. A comma tells readers that the introductory clause or phrase has come to a close and that the main part of the sentence is about to begin
When Irwin was ready to eat, his cat jumped onto the table.
Without the comma, readers may have Irwin eating his cat! The comma signals that HIS CAT is the subject of a new clause, not part of the introductory one.
COMMA PRACTICE
1. When my cat began hurling up another hairball on my newly cleaned down comforter I booted her off the bed.
2. At my last trip to the Fairvilla adult boutique I bought pantyhose with a seam running up the back a video on how to do interesting things with saran wrap and something else that I hope my mother doesn’t find on her next visit.
3. The book was expensive too long and really boring.
4. Whenever I walk in the rain I never take an umbrella.
5. The corkboard fell off its peg hit the floor and scattered dozens of ‘to do’ memos everywhere.
6. She was worried about what her animal-loving vegetarian date would say but she decided to wear her mink coat anyway.
7. Even though she hated cheesey dishes she politely ate the lasagna Ed's mother had made.
8. Evan was a skinny bossy man who hated mayhem yet he chose to work at Disney World's Magic Kingdom with all those screaming tired children.
9. Although many people marvel at how delicious my refried beans are I was careful to omit cooking the beans with lard for my dinner guests were observant Muslims.
10. Louise always rather bossy declared that everyone would play charades.
