* Subordinating Conjunction: This is the most common use of "when." It introduces a dependent clause that modifies the main clause, indicating time.
* Example: *I will call you when I get home.*
* Adverb: "When" can function as an adverb, asking about time.
* Example: *When will you be back?*
* Interrogative Adverb: "When" can also be an interrogative adverb, introducing a question about time.
* Example: *When did you leave?*.
* Pronoun: Less common, but "when" can sometimes act as a pronoun, referring to a specific time.
* Example: *I remember when we first met.* (Here, "when" refers to the time of their first meeting).
So, to know what part of speech "when" is, you need to look at its function in the specific sentence.