2. Use a comma after an introductory word, phrase, or clause. Types of introductory material that should be set off with commas:

3.  Phrase – A group of words that does NOT contain both a subject and a verb  Clause – A group of words that DOES contain both a subject and a verb, and it may or may not stand alone, depending on how it works in the sentence

4.  Introductory Words: Well, I find it difficult to decide. Yes, Charles agrees with our plan. Oh, did he really say that?

5.  Common Expressions: Of course, I’ll do it for you.  Introductory Adverbs: Certainly, you may borrow the book. Frantically, they searched for a parking spot.

6.  Prepositional Phrases: At the very top, my father paused to enjoy the view. In the heart of the city, you will find many skyscrapers.

7. NOTE: It is not absolutely necessary to set off short prepositional phrases, but sometimes you may find it necessary to avoid confusion.

8. Confusing: Inside the house walls began to crumble. Clear: Inside the house, walls began to crumble.

9.  Infinitive Phrases: To get to the train before it left, she ran all the way. To get to Broadway, they rode in a taxi.

10.  Adverb Clauses: When the team got off the plane, hundreds of onlookers began to cheer. If you intend to travel to New York this summer, you should make your plans now.