Gerund : Gerund is used as a noun in a sentence by adding ing with first of the verb. It may be in the form of subject, object as a noun.
Eg.
1. Walking is good habit.
2. Reading is my favourite pastime.
3. Swimming is good for health.
✍️ Note. Bold words are used as a subject of the verb in these sentence. And they are noun also.
1. He likes reading poetry.
2. I enjoy flying kites
✍️Note. Bold words are used as the as the object of the verb and they are noun also.
✍️Note. Gerund is used after these preposition as from, before, after, at, in, on, by, without, for, to, besides etc.
Eg.
1. On reaching home, he phoned me.
2. After taking breakfast, he went to the office.
3. He went there for walking.
4. You should abstain from smoking.