* Adjective: When "all" modifies a noun, it acts as an adjective.
* Example: "All students are required to attend." (modifies the noun "students")
* Pronoun: When "all" stands in for a noun, it acts as a pronoun.
* Example: "All of them are going to the party." (replaces the noun phrase "the people")
* Determiner: Sometimes "all" is considered a determiner, which is a type of word that precedes a noun and specifies quantity or identity.
* Example: "All the books are on the shelf." (specifies the quantity of books)
So, "all" is not strictly just one part of speech, but rather can be classified in a few different ways depending on its role in a sentence.