What is the “-ing” form of a verb?

The verb form that ends in “-ing” is known as the present participle. Present participles are used in progressive verb tenses (e.g., “I am studying,” “she had been eating”) and as adjectives (e.g., “a tiring hike”).

The “-ing” form of a verb is also used in gerunds, but gerunds operate as nouns (e.g., “Skiing is dangerous”).