The Infinitive Form is also known as the Root Form. It is when the verb is at it’s most basic form. It is the version of the verb which will appear in the dictionary. When a verb is preceded by the word to, it is said to be in its infinitive form (i.e., its most basic form). The infinitive form of a verb is usually preceded by to (e.g., to run, to dance, to think). However the infinitive form is not always preceded by to.