The Gerund

A Gerund appears in the form of an -ing verb (e.g., running) but it functions as a noun. 

It can be used as the subject of a sentence, a direct or indirect object, an object of a preposition, or a complement of a subject.  

Distinguishing between a gerund and a verb depends on the context in which it used.  For example:

• Swimming has to be the best sport ever. (Swimming is gerund because it is functioning as a subject noun.)
• I went swimming today. (Not a gerund because it is functioning as part of the verb phrase went swimming.  In this example, swimming does not refer to an idea (noun function) but to the act of swimming (verb function). 

Gerund as the subject of a sentence

• Backpacking is a rewarding pastime.
• Stretching can loosen up muscles.
• No smoking. (i.e., no smoking is allowed)

Gerund as a direct object in a sentence

• We all love to go bowling on the weekend.
• He loves eating chips.
• She hates sleeping. 

Gerund as the object of a preposition

• They complained of hearing strange sounds from the next cabin.
• They sang about winning their independence.

Gerund as a complement to a subject

• Tim's favorite outdoor activity is fishing.
• Her best subject is reading.