A while is a time, a noun. The article a before while is a sure sign that you’re dealing with a noun. Awhile means for a time and it’s an adverb.
Read the rest at Grammar Girl : “A While” Versus “Awhile”
In general, you can think of parentheses, commas, and dashes as a continuum of marks. Parentheses are the quiet whisper of an aside, commas are the conversational voice of a friend walking by your desk, and dashes are the yowl of a pirate dashing into a fray.
Read more at Dashes, Parentheses, and Commas
My memory trick is to note that immigrants come in, and both immigrant and in start with the letter i. Many readers also wrote in to note that people who emigrate exit a country, and both emigrate and exit start with e.
Read the full post at Grammar Girl
