The basic infinitive in English is formed with 'to' plus the base form of the verb. This form does not show tense, person, or number. It is called the full infinitive. In dictionaries, verbs are listed by their base form, which matches the infinitive without 'to'.

Infinitives can function as subjects, objects, or complements in a sentence. They can also appear after adjectives and certain nouns. The role of the infinitive depends on its position and the words it follows. In each case, the meaning remains non-finite and does not mark tense.

Some verbs are commonly followed by an infinitive with 'to'. These verbs select the infinitive form rather than another construction. Memorizing these pairs helps with accurate sentence formation. The choice is a property of the verb.

Infinitives often follow adjectives to explain a reason or provide more information. The structure is typically adjective plus 'to' plus verb. This pattern is frequent with adjectives related to emotion, ability, and evaluation. The infinitive explains what or why in relation to the adjective.

The English infinitive is 'to' plus base verb and remains unchanged for tense or agreement. It functions as subject, object, or complement, and is common after certain verbs and adjectives. Mastering these patterns allows clear and flexible sentence construction with non-finite verbs.