We use the -ing form
- as the subject of a sentence. Reading a book is more tiring than watching a movie.
- after avoid, appreciate, consider, continue, deny, go (+ activities), imagine, keep, miss, save, suggest, practice, prevent, spend/waste (time/money) on, etc. Can you imagine working in a chocolate factory?
- after prepositions. I am interested in going to the book festival.
- after verbs that express like/dislikes, such as: can't stand, like, enjoy, etc. I like reading novels.
- after phrases such as: can't help, look forward to, it's no use, it's not worth, have difficulty. I can't help laughing at the joke.