When a comma IS usually used:
* After introductory phrases: This includes prepositional phrases, participial phrases, and infinitive phrases.
* After adverbs: If the adverb modifies the entire sentence, a comma is typically needed.
* After interjections: These are short exclamations like "Wow!" or "Oh no!"
* After non-restrictive clauses: These provide additional information that is not essential to the main sentence. They are set off by commas.
When a comma is NOT usually used:
* After restrictive clauses: These are essential to the meaning of the sentence and are not set off by commas.
* After short introductory phrases: If the phrase is very brief and the sentence flows smoothly without a comma, it can be omitted.
* After adverbs that are closely related to the verb: For example, "She quickly walked away."
Examples:
Commas used:
* After a long introductory phrase: "After a long day at work, I was ready to relax."
* After an introductory adverb: "Fortunately, the rain stopped before the picnic started."
* After an interjection: "Oh my goodness, that was a close call!"
* After a non-restrictive clause: "The cat, which was very fluffy, sat by the fireplace."
Commas not used:
* Before a restrictive clause: "The book that I borrowed from the library was very interesting."
* Before a short introductory phrase: "In the morning, I like to have coffee."
* Before an adverb closely related to the verb: "She carefully opened the package."
Key takeaway: The best way to determine whether to use a comma before a concluding phrase is to consider the sentence's structure and flow. If the phrase is long or interrupts the natural flow, a comma will often be helpful. If the phrase is short and the sentence is clear without it, a comma may not be necessary.
Always check your work with a style guide like the Chicago Manual of Style or the AP Stylebook for specific situations.