March sentences use adjective clauses, which start with who, which, or that and modify a noun or pronoun directly in front of them. People who use them correctly use who only with people, which with places and things but never with people, and that with places or things and rarely with people. Adjective clauses that are necessary to the sentence don't take any commas, but other adjective clauses, ones that might not be necessary to the sentence, take a comma before and after the clause.
From Education Week--According to the latest research, the two best predictors of college success are not grades and intellectual ability. Number one is “conscientiousness” (dependability, perseverance, work ethic). Number two is “agreeableness” (interpersonal skills, getting along with other people, working well in groups).
From what I’ve observed, I would say the same is true for life after college—jobs and careers, marriage and family life. Success comes more easily for people who are willing to work hard and who are able to cooperate with other people.
Diet Coke and Mentos
Greek alphabet song