Gerunds vs Infinitives
Some verbs in English are followed by a gerund (-ing), some by an infinitive (to + verb), and some can take both.
Gerunds (-ing)
Used as the subject of a sentence, after prepositions, and after certain verbs (enjoy, avoid, mind).
Swimming is fun. I am interested in learning. She enjoys reading.
Infinitives (to + verb)
Used to express purpose, after adjectives, and after certain verbs (want, decide, hope).
I came here to study. It is hard to believe. They decided to leave.
Verbs that take both
Some verbs change meaning depending on what follows them (e.g., stop, remember, forget).
I stopped smoking (quit a habit) vs I stopped to smoke (paused to do an action).