Gerunds are words that are functioned as a noun. The "equation" you can use to tell if something is a Gerund or not is: Verb + -ing.
Ex. #1: Running is fun
Run is the verb, while -ing acting like a noun.
Ex. #2: Laughing is good.
It is the subject of the sentence. Laugh is the verb, while -ing acts like a noun.
Gerunds can do almost anything a noun can do! So they can be prepositional phrases too!!
Ex. #1: Running in the grass is fun!
In here the Gerund is running and the prepositional phrase is in the grass.
Ex. #2: Sliding down the waterslide is so much fun!
The Gerund is sliding and the prepositional phrase is down the waterslide.
http://www.english-grammar-revolution.com/gerunds.html
http://www.chompchomp.com/terms/gerund.htm
Ex. #1: Running is fun
Run is the verb, while -ing acting like a noun.
Ex. #2: Laughing is good.
It is the subject of the sentence. Laugh is the verb, while -ing acts like a noun.
Gerunds can do almost anything a noun can do! So they can be prepositional phrases too!!
Ex. #1: Running in the grass is fun!
In here the Gerund is running and the prepositional phrase is in the grass.
Ex. #2: Sliding down the waterslide is so much fun!
The Gerund is sliding and the prepositional phrase is down the waterslide.
http://www.english-grammar-revolution.com/gerunds.html
http://www.chompchomp.com/terms/gerund.htm