Here's how to use it:
* "Obrigado" is used by men.
* "Obrigada" is used by women.
* "Obrigada" is also used in the plural form, for both men and women when thanking a group.
Example:
* "Obrigado pela ajuda." (Thank you for your help.) - Used by a man.
* "Obrigada pelo café." (Thank you for the coffee.) - Used by a woman.
* "Obrigada pela atenção." (Thank you for your attention.) - Used by a group of women or a mixed-gender group.
Formal and informal variations:
* "Muito obrigado/a" - This translates to "Thank you very much" and is more formal.
* "Obrigado/a de coração" - This translates to "Thank you from the heart" and expresses deeper gratitude.
* "Valeu" - This is a more informal and casual way to say "thank you" and is mostly used among friends.
Remember that Brazilian Portuguese is a vibrant language, and the way you express gratitude can vary depending on the context, your relationship with the person you're speaking to, and the region of Brazil.