A Gerund is a special form of a verb. It’s also known as a Verbal Noun and more informally, the -ing form.

We use it when we want to use an action verb as the subject or object of a sentence. So essentially, it’s a verb which acts like a noun (hence the name verbal noun).

And simply put, we make it by adding -ing to the verb itself (hence the name, the -ing form).

swim > swimming
eat > eating

Note: the gerund has exactly the same form as the present participle as well as the progressive form of the verb.

Using the Gerund

Here’s a common English sentence:

{subject} + {verb} + {object}

We can use nouns (including pronouns) as a subject or object:

He likes dogs.
Dogs are fun!

And here’s a verb: swim. Turn this into a gerund by adding -ing: swimming. This can now be used as a noun in the sentence:

He likes swimming.
Swimming is fun!

Gerund vs Full Infinitive

There is also the issue of using a gerund or full infinitive in the same position. Compare these two sentences:

I like to swim.
I like swimming.

They mean pretty much the same thing. However, there are certain rules about which one it is possible to use. Although in some cases (like above) either is fine, in other cases only one will work. For example, we have to use a gerund after a preposition:

I was fined for driving too fast.
* I was fined for to drive too fast.

* an asterisk at the beginning of a sentence means it is grammatically wrong

In addition, we use either the infinitive or the gerund after certain verbs; there is no simple pattern which explains it all.

A Common Problem for Learners

One common problem learners often have is understanding the difference between these two types of usages:

The men stopped talking.
The men stopped to talk.

The first means the men were talking and then they stopped. The second means the men were doing something else which they stopped so they could talk instead.

In general you can teach that while gerunds are used for completed actions, infinitives are used for future actions.

Useful Links

Verb Forms‏‎ in English Grammar – a general look at the different forms of verbs which include the gerund.

Present Participle‏‎ in English Grammar – more on the present participle and how it’s used.