Look at the following sentences:
Alice likes teaching.
I wish to learn French.
In sentence 1 the verb likes has a subject. Its form is determined by the number and person of the subject, Alice. Verbs which are thus limited by the number and person of their subjects are called finite verbs. In fact all verbs in the indicative, imperative and subjunctive moods are finite, because they have subjects and are limited by the number and person of their subjects.
In sentence 2, the verb wish is finite because it has a subject and its form is determined by the number and person of its subject, namely I. But ‘to learn’ has no subject and is not limited by number and person. It is used without any change, whatever be the subject of the sentence – ‘You wish to learn’, ‘He wishes to learn’, ‘They wish to learn’, etc. It is therefore described as a non-finite verb, and its specific name is infinitive.
There are three types of non-finite verbs
1. The infinitive
To learn, to write, to work, to ask, to read etc. (Present infinitive)
To have learned, to have written, to have spoken, to have broken (Perfect infinitive)
2. The participle
Examples are: learning, reading, writing, worked, broken, written etc.
3. The gerund or verbal noun
Examples are: learning, writing, speaking, breaking etc.