A. Full Stop / Period (.) - common uses of a full stop is to indicate the end of a sentence, or to follow an abbreviation.
For example: We feed this cat every evening. / Mr. Brown does not agree with these new rules.
B. Comma (,) - A comma is often used to separate different ideas in a sentence. However, it has many other uses as well, and it is important to remember them as well. Some of the most common comma rules follow.
1) A comma separates two sentences when putting a full stop between them seems to create an unnecessarily long pause.
For example: Mark went by bus, and Allison took a train.
2) Commas separate items in a list.
For example: We bought apples, peaches, grapes, and oranges in the fruit market.
3) A comma is used after an introductory word or phrase, such as at the end of the day, however, in contrast, etc.
For example: Nevertheless, we managed to get home until sunset.
4) If you have a tag question at the end of your sentence, you also need to use a comma to distinguish it from the rest of the sentence.
For example: You are going to the party this weekend, aren’t you?
5) If you are directly addressing someone, you need a comma.
For example: James, what are you doing tomorrow after school?