Ex - "I went running, and i saw a duck."
2. Use a comma after a dependent clause that starts a sentence.
Ex - "When i went running, i saw a duck."
3. use commas to offset appositives from the rest of the sentence.
Ex - "A mallard, a kind of duck, attacked me."
4. Use commas to separate items in a series.
Ex - I saw a duck, a magician, and a liquor store when i went running."
5. Use a comma after introductory adverbs.
Ex - Unsurprisingly, i saw a duck when i went running."
6. Use a comma when attributing quotes.
Ex - The duck said, "Quack!"
7. Use a comma to separate each element in an address. Also use a comma after a city state combination within a sentence.
Ex - "Cleveland, Ohio, is known for their duck population."
8. Also use a comma to separate the elements in a full date.
Ex - "Friday, January 13th, 2017, will be rubber duckie day."
9. Use a comma when the first word of the sentence is freestanding "Yes" or "No."
Ex - "Yes, the duck bit me."
10. Use a comma when directly addressing someone or something in a sentence.
Ex - "Duck, do you mind?"
11. Use a comma between two adjectives that modify the same noun.
Ex - "I saw the big, mean duck when i went running."
12. Use a comma to offset negation in a sentence.
Ex - I saw a duck, not a baby seal, when i went running."
13. Use commas before every sequence of three numbers when writing a number larger than 999.
Ex - "The duck had over 10,000 friends."