Gerunds are nouns that are formed from verbs by adding -ing. (The gerund of a verb looks exactly like the present participle. As with present participles, sometimes you have to double a consonant or delete a final -e before adding -ing.)
Using a gerund is a good way to talk about the activity or process of doing the verb, usually for a period of time. For example, consider the verb travel, which means "to go on a trip or journey." Add -ing, and you have the gerund traveling, and it can be used to talk about the activity of traveling, as in this example:
We love traveling by train.
Because it's a noun, a gerund can be the subject or object of a verb, or the object of a preposition, as shown in these examples:
Skiing is my favorite sport. (Skiing is the subject of is.)
Russ prefers snowboarding. (Snowboarding is the object of prefers.)
New skiers are often afraid of falling. (Falling is the object of the preposition of.)
One note of caution: There are a number of verbs that take objects, but cannot take gerunds as objects, such as:
want
ask
promise
A good way to find out if a verb can take a gerund as an object is to look the verb up in Merriam-Webster's Learner's Dictionary. If you don't see any example sentences with gerund objects, you'll know it's probably not a good idea. There will be more to come about this in a later post.