Punctuating Pauses with Commas
Commas can warn readers of brief pauses and shifts of focus in a sentence. Use commas to indicate pauses in these situations:
To Set Off Non-Essential Information
If information could be removed from a sentence without changing the basic meaning, set off the information with commas.
Edwin, who used to play saxophone, marched with the brass band.
To Set Off Interruptions
Use a comma(s) to set off a word, phrase, or clause that interrupts the main thought of a sentence.