Gerunds

Gerunds are defined as the -ing form of a verb. They have several functions.

1. Used as subjects and complements

Skiing is my favorite sport.
Hiking can be very strenuous.
Seeing is believing

2. Used as objects following prepositions and prepositional expressions

Thanks for tending my children.
The job consists of typing, filing, and answering the phone.

3. Used as objects following certain verbs.*

The children enjoyed watching the parade.
Ms. Terrell avoided paying her taxes until it was too late. 

With some verbs you can use the structure verb + somebody + -ing. 

I can't imagine George riding a motorbike. 

You can't stop me doing what I want. 

Gerunds can sometimes take objects of their own:

Roland is afraid of making mistakes.
Sandy is considering leaving New York.

*These verbs are commonly followed by gerunds.

admit begin discuss hate love practice regret stop

advise can't help dislike hesitate mention prefer remember suggest

anticipate complete enjoy imagine mind quit resent threaten

appreciate consider finish intend miss recall resist tolerate

attempt delay forget keep neglect recollect risk try

avoid deny go like postpone recommend start understand

SOURCE:  http://www.eslgold.com/grammar/gerunds.html