Everyday Brazilian Portuguese is relaxed and informal, but courtesy still matters. These phrases will carry you through any day in Rio:

Portuguese	English	When
Por favor	Please	With any request: Um café, por favor.
Obrigado / Obrigada	Thank you	Muito obrigado / obrigada — thank you very much
De nada	You're welcome	Literally “of nothing”
Com licença	Excuse me	To get past someone, to come in, or to interrupt
Desculpa	Sorry	Informal; desculpe is a little more formal
Tchau	Bye	Informal, and used everywhere