It's an adverb, answering the question 'when'? An adverb can modify a verb, an adjective, or another adverb.
'Often' modifying a verb ('goes'): My sister often goes to the movies by herself.
'Often' modifying an adjective ('late'): Jake is often late for dinner.
'Often' modifying another adverb: [I can't think of an example.]
adverb
Adding or subtracting a suffix often changes a word's part of speech.
A suffix changes a word's part of speech. For example, the word 'happy' is an adjective. But when you add a suffix, which is an ending, it can change the part of speech. Happily is an adverb. Happiness is a noun.
Nearly is an adverb. Adverbs often end in '-ly'.
An adverb, an adverb of frequency, because it tells how often you did the verb.
Often is an adverb
Often is an adverb, and wore is a verb.
preposition
adverb
Often is an adverb, and wore is a verb.
Adding or subtracting a suffix often changes a word's part of speech.
A suffix changes a word's part of speech. For example, the word 'happy' is an adjective. But when you add a suffix, which is an ending, it can change the part of speech. Happily is an adverb. Happiness is a noun.
It can be more than one part of speech. My mistakes are legion. (= noun) He often mistakes me for someone else. (=verb)
Sashay is a verb. It means to walk in an exaggerated, showy manner, often with hip swaying.
Adverb
No, "eww" is not a traditional part of speech like a noun or verb. It is an interjection, often used to express disgust or disdain in informal language.
A preschool can be a noun, but often it's used as an adjective.