Do you want to come in? In the above sentence, the word "In" is a/an:
Do you want to come in? In the above sentence, the word "In" is a/an:
Explanation
Several words are sometimes used as adverbs or sometimes used as prepositions.
A word is a preposition when it governs a noun or a pronoun, It is an adverb when it does not.
Do you want to come in? “In” is an adverb here
Is he in his room? “In” is a preposition here