Use a period by writing a simple sentence that contains one idea. For example, "Go." is a simple sentence that uses a period.
Use a comma by inserting it in a list. For example, "Go to the market to get bananas, ice cream and milk."
Place a semicolon into a sentence when you are joining two sentences that are closely connected. For example, "Go to the market to get bananas, ice cream and milk; we're making milkshakes."
Insert a colon when you want to introduce a list. For example, "Here's what I need you to get at the market: bananas, ice cream and milk."
Use an exclamation mark when you want to express enthusiasm or make a point. For example, "Go to the market to get bananas, ice cream and milk; we're making milkshakes!"
Write out abbreviations before you include them in your text. Then include them in brackets for the first time. For example, North Atlantic Treaty Organization (NATO).
Use "who" when referring to a person and "which" when referring to an object. For example, John, who is a person, is different from the manikin, which is a dummy.