English has two ways to turn a verb into something that behaves like a noun. The gerund is the -ing form (swimming, reading, cooking). The infinitive is to + the base verb (to swim, to read, to cook). Both name an activity rather than describe an action happening at a particular moment.
The forms look different, but the job is similar — each one takes a verb and lets it sit in a sentence where a noun would normally go.
The two forms side by side
| FORM | HOW TO BUILD IT | EXAMPLE |
|---|---|---|
| Gerund | verb + -ing | reading, cooking, travelling |
| Infinitive | to + base verb | to read, to cook, to travel |
The gerund feels more common as a free-standing noun (Reading helps). The infinitive feels more common after another verb (I want to read). Both patterns are worth learning because English chooses between them depending on what comes before.
Three roles of the gerund
A gerund can do anything a noun can do. Three positions cover almost every case you'll meet.
1. Subject of a sentence
The gerund sits at the front and the sentence says something about it.
2. Object after certain verbs
Some verbs expect a gerund after them. Enjoy, finish, avoid, mind, suggest, practise are common examples.
The full list of these verbs is covered separately.
3. Object of a preposition
After any preposition — for, in, of, about, at, on, before, after — a verb must take the -ing form. Infinitives cannot follow a preposition.
Three roles of the infinitive
The infinitive also has three everyday uses.
1. After certain verbs
Many verbs are followed by to + base verb. Want, decide, hope, plan, need, agree, learn belong to this group.
2. After adjectives
When an adjective describes an action or experience, an infinitive follows.
3. To show purpose
An infinitive can explain why someone did something. In this role it replaces the phrase in order to.
Gerund or present participle?
Both end in -ing, and this overlap confuses many learners. The spelling is identical — the function is what separates them.
A gerund acts as a noun. A present participle acts as an adjective or forms a continuous tense.
If the -ing word could be replaced by a regular noun like music or coffee, it's a gerund. If it's describing what someone is doing right now, it's a participle.
A note on the bare infinitive
There is also a bare infinitive — the base verb with no to in front (go, see, work). It appears after modal verbs (can go, must see), after make and let (let me go, made him wait), and after perception verbs in certain patterns (I saw her leave). These patterns are covered separately.
Common mistakes
Using -ing after to
Using a bare infinitive after want, hope, decide
Infinitive after a preposition
Gerund confused with present continuous
Wrong form after common verbs