* Indefinite Pronoun: When "all" refers to a general or unspecified group of people or things, it functions as an indefinite pronoun. For example: "All are welcome."
* Quantifier: "All" can also act as a quantifier, indicating the entirety of something. For example: "All the students passed the test."
* Adjective: In some cases, "all" modifies a noun, making it an adjective. For example: "All dogs are good boys."
It's important to consider the context to determine the specific pronoun type.