When to use a comma and when to use a dash?

Answer 1

There are many reasons to use a comma. One is as the written equivalent of a pause-- it makes you briefly slow down when you are reading it. Commas are also what you would normally use to separate clauses in a sentence. And commas are used for making lists. Examples of each: (1) I thought about calling him, but I decided not to do it. (2) Because she studied hard, she got an excellent score on the test. (3) Apples, peaches, plums, and grapes are really good at this time of year. One reason NOT to use a comma-- you cannot connect two complete sentences with a comma; you must use a period or a semi-colon.

As for a dash, it is not like a comma at all. In fact, a dash gives more emphasis than a comma, and is often used when the person speaking suddenly has a new thought and wants to include it in the sentence even though it's really an aside. When reading a sentence with a dash it often calls for a full stop, like an interjection, even though it is part of the sentence. Most writing teachers would tell you to avoid using dashes, since they are very hard to use correctly. In fact, anything that is set off by dashes could just as easily have been presented as a separate sentence instead. For example: Yesterday, I was eating cheese -- I would have preferred to eat fish -- and I was drinking Orange Juice. (Or you could avoid the dash: Yesterday I was eating cheese and drinking orange juice. I would have preferred to eat fish.)

Answer 2

A comma is typically used to separate individual items in a list or to separate clauses within a sentence. A dash is used to indicate a break or interruption in thought or to emphasize information within a sentence. It is important to note that a dash should be used sparingly, while commas are more common in writing.