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., the present continuous: ‘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‘).