Using a Comma: Nonessential Clauses

We use commas:

1. With clauses that are not sentences.


  • After three months of hard work, he managed to collect enough money.

Shortly before the match, both team expressed optimism.

2. When we want to express parenthetical thoughts/give additional information without which our sentece still makes sense.


  • That man over there, who you took to be the boss, is my brother.