What part of speech is the word sitting?

The word "sitting" can be either a present participle or a gerund, depending on its role in the sentence.

Present participle:

* Used to describe an ongoing action.

* Often used with a helping verb (e.g., is, am, are, was, were, has, have, had).

Example: The cat is sitting on the windowsill.

Gerund:

* Functions as a noun.

* Can be the subject of a verb, the object of a verb, or the object of a preposition.

Example: Sitting in the park is my favorite way to relax.

To determine which part of speech "sitting" is, consider its function within the sentence.