What are gerunds and gerund phrases?

A gerund is a present participle used as a noun. A present participle is a verb formed by adding "-ing" to the infinitive of the verb.

A gerund phrase starts with a present participle and includes other words that work with the participle. The entire unit functions as noun in the sentence.

A gerund phrase can contain complements and modifiers.

Examples of gerund phrases

1. Studying marine life was Rachel Carson’s career.
"Studying" is the present participle; "marine life" is the direct object of the participle, telling us what is studied. The entire gerund phrase functions as the subject of the sentence.

2. She devoted herself to protecting the environment.
"Protecting" is the present participle; "the environment" is the direct object of the participle, telling us what is protected. The entire gerund phrase functions as the object of the preposition "to."

3. She loved informing the world about the need to protect endangered species.
"Informing" is the present participle; "the world" is the direct object of the participle, telling us who is informed; "about the need to protect endangered species" is a phrase modifying the participle. (Notice the adjectival infinitive phrase modifying "need.")

Confusing "-ing" words

• Since a gerund is made from a present participle, it is easy to confuse it with other forms that use the present participle. A participial phrase that uses a present participle is always used as an adjective. Be careful not to mix it up with a gerund phrase, which is always used as a noun.
• The present participle is also used in the progressive verb form. Be careful to look at how the present participle is being used in the sentence. If it is part of the verb phrase, it is not a gerund.