Here's a breakdown:
1. Independent Clauses:
* No comma: If the phrase after the verb is a necessary part of the main clause, no comma is needed.
* Example: "The cat slept soundly all day."
* Comma: If the phrase after the verb is an independent clause (can stand alone as a sentence), a comma is used to separate the clauses.
* Example: "The cat slept soundly all day, and he dreamed of mice."
2. Dependent Clauses:
* Comma: If the phrase after the verb is a dependent clause (cannot stand alone as a sentence), a comma is usually used to separate it from the main clause.
* Example: "The cat slept soundly all day, even though he was hungry."
3. Introductory Phrases:
* Comma: If the phrase after the verb is an introductory phrase (like a prepositional phrase or an adverb), a comma is often used.
* Example: "The cat slept soundly all day, in his favorite basket."
4. Interjections and Parentheticals:
* Comma: A comma is often used to separate interjections (words that express sudden emotion) or parentheticals (phrases that add extra information) from the main clause.
* Example: "The cat slept soundly all day, oh, how he needed the rest!"
Important Note:
The specific rules for comma usage can be complex, and sometimes there are stylistic preferences. If you are unsure, consult a style guide or grammar book.