A verb which is limited by the number and person of its subject is called a finite-verb.
Consider the examples given below.
- I sing.
- Ann sings.
- They sing.
The verb sing changes its form according to the number and person of its subject. Sing is therefore finite in the above sentences.
The label finite is also applied to a verb-form which is marked for tense. In the present tense, only the third person singular receives a marking for tense: the ending –s. So, for example, in Ann smokes, the verb-form smokes is finite. The form smoke is also finite in I smoke, You smoke and They smoke.
A verb can be finite in one sentence and non-finite in another sentence.
So, for example, in I want to sing, John wants to sing and I heard him sing, the verb sing is not finite. It is not affected by the changes in the number and person of the subject. It is also not affected by the changes in tense.
A verb-form which is not marked for tense.
A non-finite verb cannot be the only verb in a clause.
A typical English verb usually has the following non-finite forms – the present participle, the past participle, the infinitive and the gerund.
- I want to swim.
- Smoking is injurious to health.
- Driven by rain we took shelter under a tree.