What is the difference between dayo and desu? I was participating in a chat and a person said genki dayo. I am assuming that dayo and desu mean the same thing and can be used interchangeably. Thank you.
です is polite form. だよ is casual and friendly. You shouldn't use them interchangeably.
If you use だよ to your boss or unfamiliar people, they would think you are rude.