EG: Studying is good for you.
Gerunds are used after prepositions, but not usually after 'to'. The gerund looks identical to the present participle, which is used after the auxiliary verb 'to be', but are not the same as they do not function as main verbs. Gerunds are used after certain words and expressions, as is the infinitive, so it is useful to try to learn which form an adjective, etc., takes.
See Also: Irregular Verb; Auxiliary Verb; Ditransitive Verb; Dynamic Verb; Finite Verb; Inchoative Verb; Intransitive Verb; Modal Verb; Non-finite Verb; Phrasal Verb; Regular Verb; Stative Verb; Transitive Verb; Verb Group; Verb Phrase
Category: Gerunds and Infinitives