Formal:
* Compartilhar: This is the most general and widely used word for "to share".
* Partilhar: This word is also used for "to share" and is often used in more formal contexts.
* Dividir: This literally means "to divide" but can also be used to mean "to share".
Informal:
* Dividir: Similar to the formal usage, this word can also be used informally.
* Repartir: This is similar to "to divide" and is often used in the context of splitting something equally.
Examples:
* Vamos compartilhar a pizza? (Let's share the pizza?)
* Ele partilhou a sua história comigo. (He shared his story with me.)
* Quero dividir a conta com você. (I want to split the bill with you.)
* Repartir os lucros da empresa. (To share the company's profits.)
The best word to use depends on the context and the level of formality.