Watch this little presentation to see gerunds in our world today.
As you can see gerunds all around us. For example, "spit" is a verb. I spit on the floor. When we say, "Spitting on the floor of this car is a misdemeanor," spitting turns into a gerund. Remember that a gerund must have "ing."
A gerund is a verb used as a noun. What does a noun do in the sentence? It may act as the subject, direct object, predicate noun, or the object of a preposition.
Examples:
Subject: Spitting on the floor is nasty.
Direct Object: My children do not appreciate my singing.
Predicate Noun: My favorite activity is sleeping. (Remember that a predicate noun must have a linking verb before it.)
Object of a Preposition: I will call you after arriving at home.
For each of these examples, you may say I spit, sing, sleep, arrive, and the words act as a verb. As a gerund, the verb is a noun.