What is the “-ing” form of a verb?

The “-ing” form of a verb is called the present participle. Present participles can be used as adjectives (e.g., “a thrilling story”) and to form the continuous verb tenses (e.g., “We are partying”).

Gerunds also use the “-ing” form of a verb, but they function only as nouns (e.g., “I don’t enjoy studying”).