"WHO'S" and "WHOSE"

"Who's" is a contraction for "who is." "Whose" indicates possession. Ex.: Who's attending the conference? Whose jacket is this?

"PRINCIPAL" and "PRINCIPLE"

"Principal" refers to a person in a position of authority or the primary part of something. "Principle" means a fundamental rule or belief. Ex.: The school principal addressed the students. The principal reason for our success is teamwork. Honesty is an important principle to uphold.