Gerund is a verb form that allows verbs to function as nouns.
- Cigarettes are bad for your health.
- Smoking cigarettes is bad for your health.
In sentence 1, the subject is a noun ('cigarettes'). In sentence 2, the subject is a gerund verb phrase ('smoking cigarettes').
Gerunds take the same -ing ending as the present participle:
- I am eating. → Eating too much is unhealthy.
- She is singing. → She likes singing.
We use gerunds as:
- subjects: Hiking is good for your health.
- objects: He enjoys hiking.
- subject complements: My favorite activity is hiking.
- objects of prepositions: I asked him about hiking up Mt. Everest.
This lesson covers the first two functions.