1. Abraham Lincoln was elected to his second term in 1864, but he did not serve out his full term.

This is a compound sentence – a sentence with two independent clauses. They should be connected with a conjunction, and the comma should come before the conjunction. In this case, the conjunction is “but.

2. Claude Monet, the famous impressionist painter, lived around the turn of the century.

Commas should surround an appositive phrase. In this sentence, “the famous impressionist painter” is an appositive phrase – on that renames the noun Claude Monet.

3. After seeing him lying there, the boy ran for help.

A comma should separate an introductory clause from the rest of the sentence.

4. Three of the nation’s largest circulation newspapers are USA Today, the New York Times and the Wall Street Journal.

Commas should separate items in a series. AP style says that a comma is unnecessary between the next-to-the-last item and the conjunction – in this case, “Times” and “and.”

5. “She should not have been out that late,” the father said.

A comma should be placed between a direct quotation and the attribution. The comma should be inside the quotation marks.

6. Bill Clinton of Hope, Ark., was elected president in 1992.

Use a comma to separate the name of a town and a state from the rest of the sentence.

7. “Yes, I was there when it happened,” the witness said defiantly.

A comma should set off "yes" and "no" from the rest of the sentence.

8. She cautioned him to be silent, not to speak and not even to breathe.

This sentence contains a series of actions, but it doesn’t make sense without the well-placed comma after silent.

9. He was born in London, England, in 1939 and moved to America two years later.

When a city and a country are mentioned in a sentence, a comma should separate the name of the country from the rest of the sentence.

10. The letter said he would arrive on Nov. 15, 1980, but he never was seen again.

A comma is necessary between the day and year in a date.